Why cancer cells tend to spread to certain parts of the body?

Where a cancer starts often plays a role in where it will spread. Most cancer cells that break free from the original tumor are carried in the blood or lymph until they get trapped in the next “downstream” organ or set of lymph nodes. Once the cells are there, they can start new tumors. This explains why breast cancer often spreads to underarm lymph nodes, but rarely to lymph nodes in the groin. Likewise, there are many cancers that commonly spread to the lungs. This is because the heart pumps blood from the rest of the body through the lungs’ blood vessels before sending it elsewhere. The liver is a common site of spread for cancer cells that start in the colon because blood from the intestines flows into the liver.

Cancer cells often break away from the main (primary) tumor and travel through the blood and/or lymph system, but they don’t always settle in and start new tumors. Most of the time, the cells that broke away die. When cancer does spread to other organs and start to form new tumors, it’s because of certain genetic changes in the cells that scientists are now starting to understand. Someday, doctors may be able to tell if a person’s cancer is the type that will spread to other organs by looking for these genetic changes. Research is also focusing on treatments that block or target these genetic changes so the cancer cells can’t spread and grow.

Sometimes the patterns of spread cannot be explained by where things are in the body. Some cancer cells are able to find and invade certain sites far away from where they started. For example, advanced prostate cancer often moves into the bones before spreading to other organs. This “homing” pattern may be caused by substances on the cancer cell surfaces that stick to cells in certain organs.

Metastatic Cancer

Key Points

• Metastatic cancer is cancer that has spread from the place where it first started to another place in the body.
• Metastatic cancer has the same name and same type of cancer cells as the original cancer.
• The most common sites of cancer metastasis are, in alphabetical order, the bone, liver, and lung.

1. What is metastatic cancer?

   
   Metastatic cancer is cancer that has spread from the place where it first started to another place in the body. A tumor formed by metastatic cancer cells is called a metastatic tumor or a metastasis. The process by which cancer cells spread to other parts of the body is also called metastasis.
   Metastatic cancer has the same name and the same type of cancer cells as the original, or primary, cancer. For example, breast cancer that spreads to the lung and forms a metastatic tumor is metastatic breast cancer, not lung cancer.
   Under a microscope, metastatic cancer cells generally look the same as cells of the original cancer. Moreover, metastatic cancer cells and cells of the original cancer usually have some molecular features in common, such as the expression of certain proteins or the presence of specific chromosome changes.
   Although some types of metastatic cancer can be cured with current treatments, most cannot. Nevertheless, treatments are available for all patients with metastatic cancer. In general, the primary goal of these treatments is to control the growth of the cancer or to relieve symptoms caused by it. In some cases, metastatic cancer treatments may help prolong life. However, most people who die of cancer die of metastatic disease.
   

2. Can any type of cancer form a metastatic tumor?

   
   Virtually all cancers, including cancers of the blood and the lymphatic system (leukemia, multiple myeloma, and lymphoma), can form metastatic tumors. Although rare, the metastasis of blood and lymphatic system cancers to the lung, heart, central nervous system, and other tissues has been reported.
   

3. Where does cancer spread?

   
   The most common sites of cancer metastasis are, in alphabetical order, the bone, liver, and lung. Although most cancers have the ability to spread to many different parts of the body, they usually spread to one site more often than others. The following table shows the most common sites of metastasis, excluding the lymph nodes, for several types of cancer:
   
   

   Cancer type	Main sites of metastasis*
   Bladder	Bone, liver, lung
   Breast	Bone, brain, liver, lung
   Colorectal	Liver, lung, peritoneum
   Kidney	Adrenal gland, bone, brain, liver, lung
   Lung	Adrenal gland, bone, brain, liver, other lung
   Melanoma	Bone, brain, liver, lung, skin/muscle
   Ovary	Liver, lung, peritoneum
   Pancreas	Liver, lung, peritoneum
   Prostate	Adrenal gland, bone, liver, lung
   Stomach	Liver, lung, peritoneum
   Thyroid	Bone, liver, lung
   Uterus	Bone, liver, lung, peritoneum, vagina

   *In alphabetical order. Brain includes the neural tissue of the brain (parenchyma) and the leptomeninges (the two innermost membranes—arachnoid mater and pia mater—of the three membranes known as the meninges that surround the brain and spinal cord; the space between the arachnoid mater and the pia mater contains cerebrospinal fluid). Lung includes the main part of the lung (parenchyma) as well as the pleura (the membrane that covers the lungs and lines the chest cavity).
   

4. How does cancer spread?

   
   Cancer cell metastasis usually involves the following steps:
   
   • Local invasion: Cancer cells invade nearby normal tissue.
   • Intravasation: Cancer cells invade and move through the walls of nearby lymph vesselsor blood vessels.
   • Circulation: Cancer cells move through the lymphatic system and the bloodstream to other parts of the body.
   • Arrest and extravasation: Cancer cells arrest, or stop moving, in small blood vessels called capillaries at a distant location. They then invade the walls of the capillaries and migrate into the surrounding tissue (extravasation).
   • Proliferation: Cancer cells multiply at the distant location to form small tumors known as micrometastases.
   • Angiogenesis: Micrometastases stimulate the growth of new blood vessels to obtain a blood supply. A blood supply is needed to obtain the oxygen and nutrients necessary for continued tumor growth.
     
     
     
   Metastasis. Cancer cells invade lymph nodes and blood vessels near a tumor and spread to other parts of the body.
   Because cancers of the lymphatic system or the blood system are already present inside lymph vessels, lymph nodes, or blood vessels, not all of these steps are needed for their metastasis. Also, the lymphatic system drains into the blood system at two locations in the neck.
   The ability of a cancer cell to metastasize successfully depends on its individual properties; the properties of the noncancerous cells, including immune system cells, present at the original location; and the properties of the cells it encounters in the lymphatic system or the bloodstream and at the final destination in another part of the body. Not all cancer cells, by themselves, have the ability to metastasize. In addition, the noncancerous cells at the original location may be able to block cancer cell metastasis. Furthermore, successfully reaching another location in the body does not guarantee that a metastatic tumor will form. Metastatic cancer cells can lie dormant (not grow) at a distant site for many years before they begin to grow again, if at all.
   

5. Does metastatic cancer have symptoms?

   
   Some people with metastatic tumors do not have symptoms. Their metastases are found by x-rays or other tests.
   When symptoms of metastatic cancer occur, the type and frequency of the symptoms will depend on the size and location of the metastasis. For example, cancer that spreads to the bone is likely to cause pain and can lead to bone fractures. Cancer that spreads to the brain can cause a variety of symptoms, including headaches, seizures, and unsteadiness. Shortness of breath may be a sign of lung metastasis. Abdominal swelling or jaundice (yellowing of the skin) can indicate that cancer has spread to the liver.
   Sometimes a person’s original cancer is discovered only after a metastatic tumor causes symptoms. For example, a man whose prostate cancer has spread to the bones in his pelvis may have lower back pain (caused by the cancer in his bones) before he experiences any symptoms from the original tumor in his prostate.
   

6. Can someone have a metastatic tumor without having a primary cancer?

   
   No. A metastatic tumor is always caused by cancer cells from another part of the body.
   In most cases, when a metastatic tumor is found first, the primary cancer can also be found. The search for the primary cancer may involve lab tests, x-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, positron emission tomography (PET) scans, and other procedures.
   However, in some patients, a metastatic tumor is diagnosed but the primary tumor cannot be found, despite extensive tests, because it either is too small or has completely regressed. The pathologist knows that the diagnosed tumor is a metastasis because the cells do not look like those of the organ or tissue in which the tumor was found. Doctors refer to the primary cancer as unknown or occult (hidden), and the patient is said to have cancer of unknown primary origin(CUP).
   .
   

7. If a person who was previously treated for cancer gets diagnosed with cancer a second time, is the new cancer a new primary cancer or metastatic cancer?

   
   The cancer may be a new primary cancer, but, in most cases, it is metastatic cancer.
   

8. What treatments are used for metastatic cancer?

   
   Metastatic cancer may be treated with systemic therapy (chemotherapy, biological therapy,targeted therapy, hormonal therapy), local therapy (surgery, radiation therapy), or a combination of these treatments. The choice of treatment generally depends on the type of primary cancer; the size, location, and number of metastatic tumors; the patient’s age and general health; and the types of treatment the patient has had in the past. In patients with CUP, it is possible to treat the disease even though the primary cancer has not been found.
   

9. Are new treatments for metastatic cancer being developed?

   
   Yes, researchers are studying new ways to kill or stop the growth of primary cancer cells and metastatic cancer cells, including new ways to boost the strength of immune responses against tumors. In addition, researchers are trying to find ways to disrupt individual steps in the metastatic process.
   Before any new treatment can be made widely available to patients, it must be studied in clinical trials (research studies) and found to be safe and effective in treating disease. NCI and many other organizations sponsor clinical trials that take place at hospitals, universities, medical schools, and cancer centers around the country. Clinical trials are a critical step in improving cancer care. The results of previous clinical trials have led to progress not only in the treatment of cancer but also in the detection, diagnosis, and prevention of the disease. Patients interested in taking part in a clinical trial should talk with their doctor.

Source:www.cancer.gov

How is Prostate Cancer treated?

This information represents the views of the doctors and nurses serving on the American Cancer Society's Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.

The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.

Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don't hesitate to ask him or her questions about your treatment options.

Some general comments about prostate cancer treatment

Once your prostate cancer has been diagnosed and staged, you have a lot to think about before you and your doctor choose a treatment plan. You may feel that you must make a decision quickly, but it is important to give yourself time to absorb the information you have just learned. Ask questions of your cancer care team. Read the section "What should you ask your doctor about prostate cancer?"

Depending on the situation, the treatment options for men with prostate cancer may include:

• Expectant management (watchful waiting) or active surveillance
• Surgery
• Radiation therapy
• Cryosurgery (cryotherapy)
• Hormone therapy
• Chemotherapy
• Vaccine treatment
• Bone directed treatment

These treatments are generally used one at a time, although in some cases they may be combined.

The treatment you choose for prostate cancer should take into account:

• Your age and expected life span
• Any other serious health conditions you may have
• The stage and grade of your cancer
• Your feelings (and your doctor's opinion) about the need to treat the cancer
• The likelihood that each type of treatment will cure your cancer (or provide some other measure of benefit)
• Your feelings about the possible side effects from each treatment

Many men find it helpful to get a second opinion about the best treatment options based on their situation, especially if there are several choices available. Prostate cancer is a complex disease, and doctors may differ in their opinions regarding the best treatment options. Speaking with doctors who specialize in different kinds of treatment may help you sort through your options. You will want to weigh the benefits of each treatment against its possible outcomes, side effects, and risks.

The main types of doctors who treat prostate cancer include:

• Urologists: surgeons who specialize in treating diseases of the urinary system and male reproductive system (including the prostate)
• Radiation oncologists: doctors who treat cancer with radiation therapy
• Medical oncologists: doctors who treat cancer with medicines such as chemotherapy or hormone therapy

It is important to discuss all of your treatment options, including goals and possible side effects, with your doctors to help make the decision that best fits your needs.

Once you decide on a treatment plan, many other specialists may be involved in your care as well, including nurse practitioners, nurses, nutrition specialists, social workers, and other health professionals. If you’d like to know more about who may be on your cancer care team, see our document Health Professionals Associated With Cancer Care.

The next few sections describe the types of treatments used for prostate cancer. This is followed by discussion of other treatment-related topics, including things to think about when considering treatment options, typical treatment options based on the stage of the cancer, following PSA levels during and after treatment, and dealing with prostate cancer that remains or recurs after treatment.

Last Medical Review: 08/26/2013

What are the causes of Prostate Cancer?

Nobody is really sure of what the specific causes are. There are so many possible factors, including age, race, lifestyle, medications, and genetics, to name a few.

• Age
  
  Age is considered as the primary risk factor. The older a man is, the higher is his risk. Prostate cancer is rare among men under the age of 45, but much more common after the age of 50.


• Genetics
  
  Statistics indicate that genetics is definitely a factor in prostate cancer risk. It is more common among certain racial groups - in the USA prostate cancer is significantly more common and also more deadly among Afro-Americans than White-Americans. A man has a much higher risk of developing cancer if his identical twin has it. A man whose brother or father had/had prostate cancer runs twice the risk of developing it, compared to other men.
  
  Studies indicate that the two faulty genes - BRCA 1 and BRCA 2 - which are important risk factors for breast cancer and ovarian cancer, have also been implicated in prostate cancer risk. 

Genetic background may contribute to prostate cancer risk, as suggested by associations with race, family, and specific gene variants. Men who have a first-degree relative (father or brother) with prostate cancer have twice the risk of developing prostate cancer, and those with two first-degree relatives affected have a fivefold greater risk compared with men with no family history. In the United States, prostate cancer more commonly affects black men than white or Hispanic men, and is also more deadly in black men. In contrast, the incidence and mortality rates for Hispanic men are one third lower than for non-Hispanic whites. Studies of twins in Scandinavia suggest that 40% of prostate cancer risk can be explained by inherited factors.

No single gene is responsible for prostate cancer; many different genes have been implicated. Mutations in BRCA1 and BRCA2, important risk factors for ovarian cancer and breast cancer in women, have also been implicated in prostate cancer. Other linked genes include the Hereditary Prostate cancer gene 1 (HPC1), the androgen receptor, and the vitamin D receptor. TMPRSS2-ETS gene family fusion, specifically TMPRSS2-ERG or TMPRSS2-ETV1/4 promotes cancer cell growth.

Two large genome-wide association studies linking single nucleotide polymorphisms (SNPs) to prostate cancer were published in 2008. These studies identified several SNPs which substantially affect the risk of prostate cancer. For example, individuals with TT allele pair at SNP rs10993994 were reported to be at 1.6 times higher risk of prostate cancer than those with the CC allele pair. This SNP explains part of the increased prostate cancer risk of African American men as compared to American men of European descent, since the C allele is much more prevalent in the latter; this SNP is located in the promoter region of the MSMB gene, thus affects the amount of MSMB protein synthesized and secreted by epithelial cells of the prostate.

• Diet
  
  
  
  A review of diets indicated that the Mediterranean diet mayreduce a person's chances of developing prostate cancer.Another study indicates that soy, selenium and green tea, offer additional possibilities for disease prevention - however,a more recent study indicated that combination therapy ofvitamin E, selenium and soy does not prevent the progression from high-grade prostatic intraepithelial neoplasia (HGPIN) to prostate cancer. A diet high in vegetable consumption was found in a study to be beneficial.
  
  A US pilot study on men with low risk prostate cancer found that following an intensive healthy diet and lifestyle regime focusing on low meat and high vegetable and fruit intake, regular exercise, yoga stretching, meditation and support group participation, can alter the way that genes behave and change the progress of cancer, for instance by switching on tumor killers and turning down tumor promoters.
  
  Other studies have indicated that lack of vitamin D, a diet high in red meat may raise a person's chances of developing prostate cancer.


• Medication
  
  Some studies say there might be a link between the daily use of anti-inflammatory medicines and prostate cancer risk. A study found that statins, which are used to lower cholesterol levels, may lower a person's risk of developing prostate cancer.


• Obesity
  
  A study found a clear link between obesity and raised prostate cancer risk, as well as a higher risk of metastasis and death among obese people who develop prostate cancer.


• Sexually transmitted diseases (STDs) 
  
  Men who have had gonorrhea have a higher chance of developing prostate cancer, according to research from the University of Michigan Health System.


• Agent Orange
  
  Veterans exposed to Agent Orange have a 48% higher risk of prostate cancer recurrence following surgery than their unexposed peers, and when the disease comes back, it seems more aggressive, researchers say. Another study found that Vietnam War veterans who had been exposed to Agent Orange have significantly increased risks of prostate cancer and even greater risks of getting the most aggressive form of the disease as compared to those who were not exposed.


• Enzyme PRSS3 linked to aggressive prostate cancer
  
  Scientists from the Mayo Clinic, Florida, reported in Molecular Cancer Research that PRSS3, an enzyme, changes the environment of prostate cancer cells, making the cancer much more likely to metastasize.
  
  Senior researcher, Evette Radisky, Ph.D., said "This molecule is a protease, which means it digests other molecules. Our data suggests PRSS3 activity changes the environment around prostate cancer cells - perhaps by freeing them from surrounding tissue - to promote malignancy and invasiveness. I don't think PRSS3 is the only factor involved in driving aggressive prostate cancer, but it may be significant for a certain subset of this cancer - the kind that is potentially lethal."

What are the symptoms of Prostate Cancer?

During the early stages of prostate cancer there are usually no symptoms. Most men at this stage find out they have prostate cancer after a routine check up or blood test. When symptoms do exist, they are usually one or more of the following:

• The patient urinates more often
• The patient gets up at night more often to urinate
• He may find it hard to start urinating
• He may find it hard to keep urinating once he has started
• There may be blood in the urine
• Urination might be painful
• Ejaculation may be painful (less common)
• Achieving or maintaining an erection may be difficult (less common)

If the prostate cancer is advanced the following symptoms are also possible:

• Bone pain, often in the spine (vertebrae), pelvis, or ribs
• The proximal part of the femur can be painful
• Leg weakness (if cancer has spread to the spine and compressed the spinal cord)
• Urinary incontinence (if cancer has spread to the spine and compressed the spinal cord)
• Fecal incontinence (if cancer has spread to the spine and compressed the spinal cord)

What is Prostate Cancer?

Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize (spread) from the prostate to other parts of the body, particularly the bones and lymph nodes. Prostate cancer may cause pain, difficulty in urinating, problems during sexual intercourse, erectile dysfunction, or death. Other symptoms can potentially develop during later stages of the disease.

Rates of detection of prostate cancers vary widely across the world, with South and East Asia detecting less frequently than in Europe, and especially the United States. Prostate cancer tends to develop in men over the age of fifty. Globally it is the sixth leading cause of cancer-related death in men (it is now the first in the UK and second in the United States). Prostate cancer is most common in the developed world with increasing rates in the developing world. However, many men with prostate cancer never have symptoms, undergo no therapy, and eventually die of other unrelated causes. Many factors, including genetics and diet, have been implicated in the development of prostate cancer. Recently the prevalence of light pollution has been implicated in the development of prostate cancer.

The presence of prostate cancer may be indicated by symptoms, physical examination, prostate-specific antigen (PSA), or biopsy. Prostate-specific antigen testing increases cancer detection but does not decrease mortality. The United States Preventive Services Task Force in 2012 recommended against screening for prostate cancer using the PSA testing, due to the risk of over-diagnosis and over-treatment with most prostate cancer remaining asymptomatic. The USPSTF concludes that the potential benefit of testing does not outweigh the expected harms.

Management strategies for prostate cancer should be guided by the severity of the disease. Many low-risk tumors can be safely followed with active surveillance. Curative treatment generally involves surgery, various forms of radiation therapy, proton therapy or, less commonly, cryosurgery; hormonal therapy and chemotherapy are generally reserved for cases of advanced disease (although hormonal therapy may be given with radiation in some cases). Several studies suggest that masturbation reduces the risk of prostate cancer, but the results are controversial.

The age and underlying health of the man, the extent of metastasis, appearance under the microscope and response of the cancer to initial treatment are important in determining the outcome of the disease. The decision whether or not to treat localized prostate cancer (a tumor that is contained within the prostate) with curative intent is a patient trade-off between the expected beneficial and harmful effects in terms of patient survival and quality of life.

Asbestos Lung Cancer.

Asbestos lung cancer is a rare type of lung cancer, which is the most common cause of cancer death in the United States. An estimated 4,800 deaths a year are linked to asbestos lung cancer, a number that represents about 4 percent of all U.S. fatalities connected to lung cancer. The overwhelming majority of other deaths - about 90 percent - are linked to smoking.

Medical researchers first made a probable causal relationship between exposure to asbestos and lung cancer in 1935. Seven years later, a member of the National Cancer Institute confirmed asbestos as a cause of lung cancer. Study after study continued to show the cause-effect relationship of asbestos and lung cancer. By 1986, the Occupational Safety and Health Administration (OSHA) proclaimed lung cancer as the greatest risk for Americans who worked with asbestos.

Like mesothelioma, another asbestos-related cancer, lung cancer associated with asbestos is typically diagnosed at a late stage of development because of the long latency period of development and the onset of symptoms.

Similarities and Differences of Mesothelioma and Asbestos Lung Cancer: Mesothelioma and asbestos lung cancer are similar in that they can take decades to develop yet only months to spread to distant organs. And they have similar diagnostic procedures and treatment techniques. But the diseases differ in physical characteristics and non-asbestos risk factors.

How Asbestos Causes Lung Cancer

Fast Fact One study, published in the British Journal of Cancer, concluded that asbestos killed twice as many people through lung cancer than through mesothelioma.

A naturally occurring mineral found in homes, the workplace or the environment, asbestos has been mined and used for commercial purposes in North America since the late 1800s. It is now highly regulated and a number of countries (and U.S. government agencies) classify it as a human carcinogen. When someone disturbs an asbestos-containing product, they release the microscopic fibers into the air. If inhaled, these thin fibers can become trapped in the lungs. Over long periods of time, they can accumulate and cause inflammation, scarring and other critical health problems. In some cases, the fibers can even trigger the development of lung cancer.

Researchers report that the duration and concentration of asbestos exposure plays a role in the risk of developing lung cancer. The Helsinki Criteria states that the risk for lung cancer increases as much as 4 percent with each year of exposure. The Occupational Safety and Health Administration (OSHA) has demonstrated a clear association between the concentration of asbestos exposure and the risk of lung cancer, finding that the higher the concentration of asbestos fibers, the higher the risk of lung cancer.

The implications of asbestos exposure are not apparent immediately following exposure. When asbestos fibers are first inhaled, they can become lodged in the lining of the lungs. The size of asbestos fibers affects where they become lodged, having implications on whether lung cancer or mesothelioma develops. Researchers discovered that 3mm fibers are more likely to become lodged in the lining of the lungs, whereas 5mm fibers (1/5 inch) tend to lodge in the lung tissue and increase the risk of developing lung cancer.

After many years, sometimes decades, these fibers cause enough irritation and cellular damage to generate tumor formation. Whether someone develops lung cancer, mesothelioma or asbestosis will depend on a person's health, genetics, habits like smoking, and the duration and concentration of exposure.

Occupational Exposures

Workers in certain trades and professions, most of them industrial, carry elevated risks of developing asbestos-related lung cancer. Shipyards, which have notoriously poor safety records, exposed workers to widespread asbestos until the mid-1970s. Many employees rarely wore necessary protective gear, and nearly all shipyard workers placed themselves at risk for lung cancer, asbestosis and mesothelioma.

But shipyards workers are hardy the only trade considered high risk for asbestos lung cancer. Any occupation in which people are in a confined area where asbestos is present - or where asbestos dust is circulated - is dangerous.

Those occupations include:

• Auto mechanics
• Construction workers
• Insulation installer
• Roofers
• Tilers
• Plumbers

• Paper mill workers
• Textile workers
• Sheet metal workers
• Toll collectors
• Linotype technicians

Prognosis and Survival Rates

The prognosis and survival rate for someone with asbestos lung cancer differs by type and subtype of the disease and also by the stage at which the cancer is found. Overall, though, the median survival for a limited stage small cell patient, with combination chemotherapy, is 16 to 22 months. For patients with extensive stage cancer, the median survival is nine to 11 months with the same treatment.

The prognosis and survival rate for someone with asbestos lung cancer differs by type and subtype of the disease and also by the stage at which the cancer is found. Overall, though, the median survival for a limited stage small cell patient, with combination chemotherapy, is 16 to 22 months. For patients with extensive stage cancer, the median survival is nine to 11 months with the same treatment.

A 2008 review of medical literature found that adenocarcinoma is almost always associated with longer survival times. A 2011 study agreed with these findings, reporting that adenocarcinoma patients lived a median of 8.4 months while all other NSCLC patients lived a median of 8.1 months. While the difference is small, researchers believe it to be significant.

Diagnosed with Asbestos-Related Lung Cancer?

The treatment you might need for your cancer depends greatly on the type of cancer you have. Although asbestos lung cancer doctors often treat more than one form of the disease, clinical trials are develop around specific disease types and circumstances. You may qualify for one of those clinical trials because of your specific disease.