What is Cancer?
Cells and the Genetic Code: The Origins of Cancer
Cells are the basic building block of life. All living tissues are made of cells. There are hundreds of different types of cells in the body. Each type has a specific function. Blood cells carry oxygen, nerve cells carry instructions, skin cells protect our bodies, and so on.
Blood Cells Carry Oxygen
Nerve Cells Carry Instructions
Skin Cells Protect Our Bodies
This strawberry illustrates how many cancer cells can fit in one strawberry seed.
All cells contain DNA, a special kind of molecule that contains our genetic code. DNA controls all of a cell’s functions, including cell reproduction (growth). If the DNA is damaged in a certain way, the cell may reproduce uncontrollably. Uncontrolled growth is the beginning step in cancer development. Substances that cause cancer-producing DNA damage are called carcinogens (carSIN-oh-gins). Carcinogens include a few specific viruses, some natural substances (tobacco, asbestos, etc), chemicals, and some types of radiation. The interval between exposure to a carcinogen and the development of cancer is usually years to decades. There are many
carcinogens that affect humans. However, for most human cancers we cannot look back in time and identify a carcinogen or clear cause for the cancer. Indeed, most cancers in humans have no single dominant cause. Most cancers arise because of many factors, only one of which may be exposure to an identifiable carcinogen. The other factors include things like age, diet, lifestyle choices, and unique aspects of a personÃ•s genetic code that make him or her more vulnerable to developing cancer.
Cancer = Uncontrolled Growth + Ability to Spread
Cancer is defined by uncontrolled cell growth and the ability to spread and grow in other parts of the body. The first step in cancer formation is uncontrolled growth. This growth is very slow at first, and many cancers spend years or decades in this step before spreading.
The second step in cancer formation is the ability to spread to other parts of the body. Over time, growing cancer cells can change and become able to spread (metastasize) to other parts of the body. It is this ability to spread throughout the body that defines a cancer and that makes it a potentially life-threatening disease.
cultured cancer cells
Some cancers grow very slowly and almost never spread; a good example is the common skin cancer basal cell carcinoma, which is almost 100% curable. Some cancers, however, have frequently spread before they are detected; this is often the case for cancers of the lung and pancreas.
Is Cancer One Disease or Many?
There are many different types of cancer. Doctors label cancers by their place of origin. Breast cancers start in the breast, lung cancers start in the lung, etc. Some are very curable and rarely a threat to life, while others are resistant to treatment and very lethal.
Cancers of the same type may look and behave similarly. For example, breast cancers in two different women may look very similar under the microscope and may be vulnerable to the same anti-cancer drugs (chemotherapy). These common features allow doctors to predict – within reason – how a given type of cancer will behave and how it may respond to treatment. This knowledge guides doctors in making treatment recommendations. However, despite these common features, every cancer is unique, and the outcome of one person with breast cancer cannot predict the outcome of another person with breast cancer.
Is Cancer a New Disease?
Popular theories suggest that cancer is caused by pollution and is a ‘curse’ on modern society. This is incorrect. Some cancers are from human-made carcinogens, but most carcinogens are naturally occurring. Examples include tobacco, asbestos, and the cancer-causing viruses. Humans can make the unwise decisions to smoke tobacco and line buildings with asbestos, but these substances themselves are not new. Cancer is as old as life itself; it has been found in dinosaur fossils and in the mummified bodies of ancient humans.
Why is Cancer a Threat to Life?
Why do cancers threaten a patient’s life? One way is by spreading to – and damaging – other organs in the body. Cancer that spreads to the lung can cause shortness of breath and pneumonia. Cancer that spreads to the brain can cause symptoms similar to a stroke.
Cancer has other effects that may not relate to spreading to and damaging a particular organ. Many cancer cells secrete chemicals or hormones that cause weight loss, weak bones, fevers, fatigue, a vulnerability to infections, and chemical imbalances in the blood.
Breast Cancer Risk Factor
Breast cancer is the second most common cancer (after skin cancer) in women in the United States, with approximately 180,000 cases expected in 2007. It causes the death of more than 40,000 women each year, and is the second leading cause of cancer death in women.
A woman’s risk of developing breast cancer increases with age; more than three out of four breast cancer cases occur in women over age 50.
Other risk factors include:
A family history of breast cancer
A prior history of breast cancer or certain other abnormalities of the breast tissue
Increased exposure to the female hormone estrogen
Having a first menstrual period before age 13
Entering menopause after age 51
Using estrogen replacement therapy
Never having been pregnant
First pregnancy after age 30
Being overweight, especially after menopause
Drinking alcohol (cancer risk doubles with three or more drinks per day)
Having a sedentary lifestyle with little regular exercise
The most important risk factor is simply being female. Most breast cancer survivors had no family history at all! And keep in mind, fibrocystic disease is NOT a risk factor for breast cancer.
Ductal Carcinoma In Situ (DCIS)
Ductal carcinoma in situ is a highly curable form of early breast cancer. Because the cancer is confined to the milk duct, it cannot escape the breast and spread to other organs. It is most often diagnosed on a screening mammogram, and needle biopsy before surgical removal is the best approach. If treated appropriately with mastectomy or breast conservation (lumpectomy followed by radiation), the cure rate is 99%. If under-treated, ductal carcinoma in situ can grow back as a potentially life-threatening invasive breast cancer.
What is Ductal Carcinoma In Situ?
Ductal carcinoma in situ (pronounced DUCKtul carsinOHMa inSIGHT-to) is often abbreviated and spoken as the letters DCIS.
Ductal carcinoma in situ is a highly curable form of early breast cancer. The name means ‘duct cancer in the original place’ and refers to the fact that the cancer started inside the milk duct and remains confined there.
A breast cancer can only threaten life by spreading beyond the breast to other organs. It does this by entering a blood or lymph vessel in the breast. These vessels are channels that cancer cells use like highways to leave the breast. All of these channels are located outside of the breast ducts. If the cancer cells are only inside the breast duct, they cannot enter these channels and they cannot spread beyond the breast. That is the case with ductal carcinoma in situ.
If under-treated, some cases of ductal carcinoma in situ can change and become more aggressive. They ‘learn’ how to invade through the duct and then become an invasive breast cancer that can then enter blood or lymph channels and spread to other organs. The main goal of treatment of ductal carcinoma in situ is to prevent this from happening.
Some doctors describe ductal carcinoma in situ as a ‘pre-cancerous’ condition. They do this with the good intention of emphasizing the excellent cure rate. But this is not correct. Ductal carcinoma in situ is a cancer, but one with an extremely high cure rate. By calling it pre-cancerous, patients and doctors may be distracted from giving it the attention it deserves. This may lead to under-treatment. Under-treating ductal carcinoma in situ may increase the future risk of developing a life-threatening invasive breast cancer.
How is Ductal Carcinoma In Situ Diagnosed?
Most cases of ductal carcinoma in situ are detected by screening mammograms. It most commonly appears as a small sprinkling of tiny white dots of calcium on the mammogram. These are called ‘clustered micro-calcifications’. It may also appear without micro-calcifications as a shadow or mass on the mammogram. Breast ultrasound and MRI may sometimes help identify ductal carcinoma in situ, particularly in younger women with dense breasts for whom mammograms may be less effective.
The first step in diagnosing any breast cancer is a needle biopsy. Jumping to surgical removal of the lump – before needle biopsy has confirmed it to be a cancer – is a natural reflex for many patients and doctors. “I just want it out!” This reflex is understandable, but it’s not the best first step. There are very good reasons for doing needle biopsy before surgical removal. It may allow the patient to undergo one surgery for treatment rather than two. It’s even possible that the treatment will be more successful if a needle biopsy is done first.
How is Ductal Carcinoma In Situ Treated?
After lumpectomy alone for ductal carcinoma in situ, some patients experience a re-growth of the cancer at the site of the original surgery. This is called a local recurrence. Trying to remove a larger amount of breast tissue to prevent this would leave a deformed breast and defeat the purpose of breast conservation.
Fortunately, moderate doses of radiation therapy are extremely effective in wiping out the small amounts of residual ductal carcinoma in situ that remain at the edge of the surgery site. This radiation therapy can be delivered by external beam treatments delivered once daily for an average of six weeks, or by newer more targeted breast brachytherapy (internal radiation) techniques that are completed in one week.
Some women may be offered lumpectomy alone for their diagnosis of ductal carcinoma in situ. Omitting radiation therapy after a lumpectomy increases the chances of the ductal carcinoma in situ growing back in the area of the scar. When it does grow back, it can sometimes change into a more aggressive and potentially life-threatening invasive cancer. While some women may be appropriately treated with lumpectomy alone for ductal carcinoma in situ, it is not the best treatment for most women with this disease. Mastectomy and breast conservation (lumpectomy and radiation therapy) remain the two best treatment options.
Chemotherapy is only used for invasive breast cancer and has no role in the treatment of ductal carcinoma in situ. Estrogen blocking drugs (tamoxifen, letrozole, anastrazole, etc) may slightly reduce the risk of a recurrence of ductal carcinoma in situ, but these drugs are more effective in preventing new breast cancers from forming in either breast. For this reason, one of these estrogen-blocking drugs is sometimes offered as breast cancer prevention therapy after lumpectomy and radiation therapy for ductal carcinoma in situ.
Lobular Carcinoma In Situ (LCIS)
Lobular carcinoma in situ is not real breast cancer, but a condition of abnormally growing cells in the milk-producing glands. It is associated with a higher rate of breast cancer in the future (years to decades later). It is almost always diagnosed accidentally when a biopsy is done for other reasons. It is often throughout both breasts. Lobular carcinoma in situ itself is not a threat and no direct treatment of is needed. Some women will take estrogen-blocking medicines to reduce the risk of breast cancer in the future.
What is Lobular Carcinoma In Situ?
Lobular carcinoma in situ (pronounced LOB-yoo-lar car-sin-OH-Ma in-SIGHT-to) is often abbreviated and spoken as the letters LCIS.
Lobular carcinoma in situ develops in the milk-producing lobules of the breast, which are ‘upstream’ to the milk ducts.
Lobular carcinoma in situ can be a little hard to understand. Despite its name, it is not really breast cancer. Lobular carcinoma in situ is the abnormal growth of cells lining the breast lobule. These abnormal cells can fill the lobule, but remain inside the lobule, much like the cancer cells of ductal carcinoma in situ remain inside the milk-carrying duct. But aside from this one common feature, lobular carcinoma in situ is a very different and unique disease.
Why is Lobular Carcinoma In Situ Important?
Lobular carcinoma in situ identifies women who are at moderately increased risk of developing breast cancer in either breast in the years and decades to follow. It is sometimes referred to as a risk factor for developing future breast cancer.
Lobular carcinoma in situ, despite being found on a small biopsy in one part of the breast, is almost always present throughout the entire breast and very often throughout both breasts.
How is Lobular Carcinoma In Situ Diagnosed?
Lobular carcinoma in situ is almost always found accidentally. It’s most often diagnosed when a breast biopsy is done for a breast mass or in pursuit of suspicious findings (shadows, etc) on a mammogram.
The lobular carcinoma in situ is found in nearby breast tissue and is often completely unrelated to the mass or mammogram finding that prompted the biopsy. Lobular carcinoma in situ commonly involves the entire breast and is often present in the opposite breast as well.
How is Lobular Carcinoma In Situ Treated?
Other than some rare subtypes, lobular carcinoma in situ itself does not need removal or treatment. Some experts have suggested the word carcinoma should be eliminated from the name because it causes unnecessary patient distress and confusion.
After a woman is told that lobular carcinoma in situ is a ‘marker’ or risk factor (but by no means a guarantee) for future breast cancer, the natural reflex is to want that area of lobular carcinoma in situ removed. But because it is usually present in the entire breast and often throughout both breasts, removing one small area of lobular carcinoma in situ is not helpful and will not measurably reduce the future breast cancer risk.
But women with lobular carcinoma in situ can reduce this future breast cancer risk in other ways. Such treatment is called breast cancer prevention. Women with lobular carcinoma in situ (and other at-risk women such as those with a family history of breast cancer or a prior diagnosis of breast cancer) can benefit from taking estrogen-blocking drugs (tamoxifen, anastrazole, letrozole, etc) that reduce by half the risk of developing a future breast cancer. Also, some women choose to undergo risk-reducing removal of both breasts (bilateral mastectomy) to reduce the risk of future breast cancer. Some experts consider this an extreme response, but the decision is for the patient to make. Removal of both breasts should only be offered after thoughtful discussion with a breast cancer specialist about all the treatment options.
Pleomorphic Lobular Carcinoma In Situ: A Special Type
Pleomorphic lobular carcinoma in situ is an uncommon and special type of lobular carcinoma in situ that behaves differently. Pleomorphic is pronounced plee-oh-MORE-fic, and refers to the distorted and odd-shape to the cells of this type. Experts have recently shown that small areas of pleomorphic lobular carcinoma in situ can change into real breast cancer. Because of this most experts now suggest this type be treated with lumpectomy and radiation, or with mastectomy, to prevent this.
What Is Early Stage Breast Cancer?
Breast cancer is described as early stage when it is likely to be cured with standard therapy. The term “early stage” is vague, and two doctors may define it differently. But most doctors consider Stage I and Stage II breast cancer to be early stage breast cancer. These are cancers which are not larger than 5 cm and which have limited spread to the lymph nodes.
How is Early Stage Breast Cancer Treated?
The three different treatments commonly used for breast cancer are surgery, drug therapy, and radiation therapy. Surgery is used to remove the visible cancer and to inspect the lymph nodes in the armpit area (the axilla). After surgery, drug therapy and radiation therapy may be used to prevent the cancer from coming back.
Inflammatory Breast Cancer
Inflammatory breast cancer is a type of advanced breast cancer in which the breast appears red and swollen due to plugging of skin lymph channels by breast cancer cells. It may or may not have spread to nearby lymph nodes or beyond the breast to other organs.
Inflammatory breast cancer that is confined to the breast and lymph nodes (it has not spread to other organs) is potentially curable. Treatment for such cases typically includes chemotherapy first, then surgical removal of the breast, and then radiation therapy to the chest area. Inflammatory breast cancer that has spread beyond the lymph nodes to other organs may be treated the same way, but cure remains a challenge in these patients.
How Does Inflammatory Breast Cancer Behave?
Inflammatory breast cancers are faster growing than other breast cancers. This makes them more dangerous; many inflammatory breast cancers have spread to the lymph nodes in the armpit by the time they are diagnosed, and some have already spread beyond to other organs (they have metastasized).
The fast growth of inflammatory breast cancers is a great concern, but it also makes these cancers more vulnerable to chemotherapy drugs. Chemotherapy drugs are more effective against cancer cells that are growing quickly. Because inflammatory breast cancers are growing quickly, they are usually vulnerable to chemotherapy.
How is Inflammatory Breast Cancer Treated?
Many cases of inflammatory breast cancer are curable. Cure requires the use of chemotherapy, surgery and radiation therapy. Inflammatory breast cancer is treated with chemotherapy first. Surgery to remove the breast is performed next. After surgery, additional chemotherapy may be given. Radiation is the last phase of treatment, and is given to the chest wall scar area and the lymph node areas of the armpit and behind the breastbone.
Experience has taught us that chemotherapy is the best first step. Years ago surgery was tried first, but patients experienced very unpleasant re-growth of the cancer in the chest wall scar line. Chemotherapy cannot penetrate this scar tissue very well; giving the chemotherapy first avoids this problem. Also, chemotherapy is the most important treatment for inflammatory breast cancer. If the cancer is vulnerable to chemotherapy, then cure is possible, and the doctors and patient know that surgery and radiation should follow chemotherapy. If the cancer does not shrink (respond) to chemotherapy, then cure is much less likely. Surgery may not be possible at all because the wounds do not heal well if a large amount of cancer is present in the skin and breast at the time of surgery.
The best result after chemotherapy is that all the cancer disappears. The scans become normal and the red, swollen breast returns to a normal appearance. If this happens, then surgery (mastectomy) is the next step; this surgery is usually combined with removal of lymph nodes from the armpit (axillary lymph node dissection).
If all the cancer disappears after chemotherapy, why remove the breast? We know from experience that invisibly small amounts of cancer almost always remain in the breast, even if it appears all the cancer has disappeared. Surgery helps remove much or all of this residual cancer and greatly improves the cure rate.
After chemotherapy and surgery, radiation therapy is almost always added as the final treatment. Again, even if all the cancer has disappeared after chemotherapy and surgery, experience shows that invisibly small amounts of cancer can be left behind after chemotherapy and surgery. This cancer can grow back (recur) in the chest wall scar area, or in the skin, or in the lymph node areas. Radiation therapy can sterilize these remaining cancer cells and prevent these recurrences. Radiation therapy improves the cure rate for inflammatory breast cancer.
These are very difficult problems to treat and are best prevented with radiation therapy after chemotherapy and surgery.
Inflammatory breast cancer may have spread to other organs by the time it is diagnosed. It is then called metastatic inflammatory breast cancer. Patients are often treated with the same approach: chemotherapy, surgery and radiation therapy. Metastatic inflammatory breast cancer may be controlled with this treatment for a long time, but cure for patients with metastatic inflammatory breast cancer remains a challenge.
What is Metastatic Breast Cancer?
Why Is Metastatic Breast Cancer A Threat To Life?
Breast cancer growing in another organ – such as the lungs, the liver, or the brain – can damage that organ. Damaged lungs can result in breathing problems and pneumonia. A damaged liver can cause life-threatening chemical imbalances in the blood. Breast cancer that has spread to the brain may cause symptoms similar to a stroke. This direct damage to other organs is one way metastatic breast cancer can threaten life. Organs commonly involved by metastatic breast cancer include bones, the lungs, the liver, and the brain.
How Does Breast Cancer Spread (Metastasize) To Other Organs?
How is Metastatic Breast Cancer Diagnosed?
Metastatic breast cancer is diagnosed when breast cancer tissue is confidently found in another organ of the body.
Metastatic breast cancer may be strongly suggested by finding an abnormal lump in another part of the body during physical examination. Often a CAT scan or other type of test may raise the concern that the cancer has metastasized. A biopsy is often done to confirm the diagnosis of metastatic breast cancer.
How is Metastatic Breast Cancer Treated?
The main treatment of metastatic breast cancer includes some form of drug therapy. These include:
targeted or biologic drugs
Genetic Breast Cancer
There are some families that have a very high rate of women getting breast cancer. Until 1990, we did not understand these families. In 1990, the first of two genes were identified that when mutated caused a woman to have a very high risk of getting breast cancer. In 1994, the sequencing of this gene was completed and we could begin to sequence the gene in women to see if they had the mutation that placed them at high risk for getting breast cancer.The second gene, BRCA2 was discovered and sequenced in 1994 and 1995.
To date, most inherited cases of breast cancer have been associated with two genes: BRCA1, which stands for BReast CAncer gene one, and BRCA2, or BReast CAncer gene two. The function of these genes is to keep breast cells growing normally and to prevent any cancer cell growth. But when these genes contain abnormalities, or mutations, they are associated with an increased breast cancer risk. Abnormal BRCA1 and BRCA2 genes may account for up to 10% of all breast cancers.
For a long time, many of us thought that breast cancer susceptibility was inherited through the maternal relatives. This is not the case with the mutations of the BRCA genes in women. These mutated genes can be inherited from either parent. Cases of breast and ovarian cancer may seem to skip a generation, when being carried by a male, but may well appear in females in the next generation. Remember, breast cancer can occur in men, usually associated with a mutation of BRCA2.
Remember also that the gene is one complex area on a single chromosome and within that gene are multiple spots where alterations (mutations) can occur, over 200 in the BRCA1 and BRCA2 genes combined.
It is important that families with genetic breast cancer be identified. For women with a BRCA mutation, they will have a 70-85% lifetime risk of developing a single cancer and an elevated risk of developing ovarian cancer. If a woman has a breast cancer and a BRCA mutation, she may have as high as a 50% risk of developing a second breast cancer within the first 10 years after her first. If a family member has a BRCA mutation, her sisters and daughters will have a 50% of risk of inheriting the same mutation and having up to a 85% risk of developing their own breast cancer – sons and brothers will have the same risk of inheriting a mutation, but a much lower risk of developing a cancer.
Is Cancer Curable?
The type and location of a cancer is important. Many breast cancers are small and curable when detected. Very early cancers of the voice box (larynx) are 99% curable. Some cancers are ‘silent’ until they are advanced and are more difficult to cure.
The outcome of one patient with breast cancer (or prostate cancer, etc.) does not predict the outcome of another person with that same cancer. Every cancer is unique. While general statements in books or on websites can be helpful, they are no substitute for a face-to-face consultation with a specialist.