ONCOLOGY & CANCER TREATMENT
Cancer is a class of diseases characterized by out-of-control cell growth. There are over 100 different types of cancer, and each is classified by the type of cell that is initially affected.
Cancer harms the body when altered cells divide uncontrollably to form lumps or masses of tissue called tumors (except in the case of leukemia where cancer prohibits normal blood function by abnormal cell division in the blood stream). Tumors can grow and interfere with the digestive, nervous, and circulatory systems, and they can release hormones that alter body function. Tumors that stay in one spot and demonstrate limited growth are generally considered to be benign.
More dangerous, or malignant, tumors form when two things occur:
- a cancerous cell manages to move throughout the body using the blood or lymphatic systems, destroying healthy tissue in a process called invasion
- that cell manages to divide and grow, making new blood vessels to feed itself in a process called angiogenesis.
When a tumor successfully spreads to other parts of the body and grows, invading and destroying other healthy tissues, it is said to have metastasized. This process itself is called metastasis, and the result is a serious condition that is very difficult to treat.
According to the American Cancer Society, Cancer is the second most common cause of death in the US and accounts for nearly 1 of every 4 deaths. The World Health Organisation estimates that, worldwide, there were 14 million new cancer cases and 8.2 million cancer-related deaths in 2012 (their most recent data).
Individual Types of Cancer
There are said to be over 200 different types of cancer. We have the following common cancer types covered in individual Knowledge Center articles:
- Anal cancer
- Bladder cancer
- Bone cancer
- Breast cancer
- Cervical cancer
- Colon cancer
- Colorectal cancer
- Endometrial cancer
- Kidney cancer
- Liver cancer
- Ovarian cancer
- Pancreatic cancer
- Prostate cancer
- Stomach cancer
- Testicular cancer
- Thyroid cancer
- Vaginal cancer
- Vulvar cancer
The rest of this article will focus on what cancer is, what causes cancer, the symptoms, diagnosis and available treatments.
Fast Facts on Cancer
Here are some key points about cancer. More detail and supporting information is in the main article.
- Cancer is considered to be one of the leading causes of morbidity and mortality worldwide.
- African Americans are more likely to die of cancer than people of any other race or ethnicity.
- It is believed that cancer risk can be reduced by avoiding tobacco, limiting alcohol intake, limiting UV ray exposure from the sun and tanning beds and maintaining a healthy diet, level of fitness and seeking regular medical care.
- Screening can locate cervical cancer, colorectal cancer and breast cancer at an early, treatable stage.
- Vaccines such as the human papillomavirus (HPV) vaccine assist in preventing some cervical, vaginal, vulvar, and oral cancers. A vaccine for hepatitis B can reduce liver cancer risk.
- According to the World Health Organization (WHO), the numbers of new cancer cases is expected to rise by about 70% over the next 20 years.
- The most common sites of cancer among men are lung, prostate, colon, rectum, stomach and liver.
- The most common sites of cancer among women are breast, colon, rectum, lung, cervix and stomach.
Symptoms of Cancer
Cancer symptoms are quite varied and depend on where the cancer is located, where it has spread, and how big the tumor is. Some cancers can be felt or seen through the skin – a lump on the breast or testicle can be an indicator of cancer in those locations. Skin cancer (melanoma) is often noted by a change in a wart or mole on the skin. Some oral cancers present white patches inside the mouth or white spots on the tongue.
Other cancers have symptoms that are less physically apparent. Some brain tumors tend to present symptoms early in the disease as they affect important cognitive functions. Pancreas cancers are usually too small to cause symptoms until they cause pain by pushing against nearby nerves or interfere with liver function to cause a yellowing of the skin and eyes called jaundice. Symptoms also can be created as a tumor grows and pushes against organs and blood vessels. For example, colon cancers lead to symptoms such as constipation, diarrhea, and changes in stool size. Bladder or prostate cancers cause changes in bladder function such as more frequent urination or infrequent urination.
Swollen or enlarged lymph nodes can be a symptom, although lymph nodes can also become swollen when fighting infection (cold or flu).
As cancer cells use the body’s energy and interfere with normal hormone function, it is possible to present symptoms such as fever, fatigue, excessive sweating, anemia, and unexplained weight loss. However, these symptoms are common in several other maladies as well. For example, coughing and hoarseness can point to lung or throat cancer as well as several other conditions.
When cancer spreads, or metastasizes, additional symptoms can present themselves in the newly affected area. Swollen or enlarged lymph nodes are common and likely to be present when the cancer starts to spread.
If cancer spreads to the brain, patients may experience vertigo, headaches, or seizures. Spreading to the lungs may cause coughing and shortness of breath. In addition, the liver may become enlarged and cause jaundice and bones can become painful, brittle, and break easily. Symptoms of metastasis ultimately depend on the location to which the cancer has spread.
Treatments for Cancer
Cancer treatment depends on the type of cancer, the stage of the cancer (how much it has spread), age, health status, and additional personal characteristics. There is no single treatment for cancer, and patients often receive a combination of therapies and palliative care. Treatments usually fall into one of the following categories: surgery, radiation, chemotherapy, immunotherapy, hormone therapy, or gene therapy.
Surgery is the oldest known treatment for cancer. If a cancer has not metastasized, it is possible to completely cure a patient by surgically removing the cancer from the body. This is often seen in the removal of the prostate or a breast or testicle. After the disease has spread, however, it is nearly impossible to remove all of the cancer cells. Surgery may also be instrumental in helping to control symptoms such as bowel obstruction or spinal cord compression.
Innovations continue to be developed to aid the surgical process, such as the iKnife that “sniffs” out cancer. Currently, when a tumor is removed surgeons also take out a “margin” of healthy tissue to make sure no malignant cells are left behind. This usually means keeping the patients under general anesthetic for an extra 30 minutes while tissue samples are tested in the lab for “clear margins”. If there are no clear margins, the surgeon has to go back in and remove more tissue (if possible). Scientists from Imperial College London say the iKnife may remove the need for sending samples to the lab.
For surgeons to distinguish between cancerous and healthy tissue. Viewed through the glasses, cancer cells appear to glow blue under a special light, thanks to a fluorescent marker injected in the tumor that attaches only to cancerous and not to healthy cells. Also, the lighter the shade of blue, the more concentrated the cancer cells are.
Promising results of an early small trial at Duke University Medical Center in Durham, NC have suggested a new injectable agent that makes cancer cells in a tumor fluoresce, could help surgeons remove all of the cancerous tissue on the first attempt. Tests continue to be carried out.
2) Radiation Radio Therapy
Radiation treatment, also known as radiotherapy, destroys cancer by focusing high-energy rays on the cancer cells. This causes damage to the molecules that make up the cancer cells and leads them to commit suicide.
Radiotherapy utilizes high-energy gamma-rays that are emitted from metals such as radium or high-energy x-rays that are created in a special machine. Early radiation treatments caused severe side-effects because the energy beams would damage normal, healthy tissue, but technologies have improved so that beams can be more accurately targeted. Radiotherapy is used as a standalone treatment to shrink a tumor or destroy cancer cells (including those associated with leukemia and lymphoma), and it is also used in combination with other cancer treatments.
Chemotherapy utilizes chemicals that interfere with the cell division process – damaging proteins or DNA – so that cancer cells will commit suicide. These treatments target any rapidly dividing cells (not necessarily just cancer cells), but normal cells usually can recover from any chemical-induced damage while cancer cells cannot. Chemotherapy is generally used to treat cancer that has spread or metastasized because the medicines travel throughout the entire body. It is a necessary treatment for some forms of leukemia and lymphoma. Chemotherapy treatment occurs in cycles so the body has time to heal between doses. However, there are still common side effects such as hair loss, nausea, fatigue, and vomiting. Combination therapies often include multiple types of chemotherapy or chemotherapy combined with other treatment options.
Immunotherapy aims to get the body’s immune system to fight the tumor. Local immunotherapy injects a treatment into an affected area, for example, to cause inflammation that causes a tumor to shrink. Systemic immunotherapy treats the whole body by administering an agent such as the protein interferon alpha that can shrink tumors. Immunotherapy can also be considered non-specific if it improves cancer-fighting abilities by stimulating the entire immune system, and it can be considered targeted if the treatment specifically tells the immune system to destroy cancer cells. These therapies are relatively young, but researchers have had success with treatments that introduce antibodies to the body that inhibit the growth of breast cancer cells. Bone marrow transplantation (hematopoetic stem cell transplantation) can also be considered immunotherapy because the donor’s immune cells will often attack the tumor or cancer cells that are present in the host.
5) Hormone Therapy
Several cancers have been linked to some types of hormones, most notably breast and prostate cancer. Hormone therapy is designed to alter hormone production in the body so that cancer cells stop growing or are killed completely. Breast cancer hormone therapies often focus on reducing estrogen levels (a common drug for this is tamoxifen) and prostate cancer hormone therapies often focus on reducing testosterone levels. In addition, some leukemia and lymphoma cases can be treated with the hormone cortisone.
6) Gene Therapy
The goal of gene therapy is to replace damaged genes with ones that work to address a root cause of cancer: damage to DNA. For example, researchers are trying to replace the damaged gene that signals cells to stop dividing (the p53 gene) with a copy of a working gene. Other gene-based therapies focus on further damaging cancer cell DNA to the point where the cell commits suicide. Gene therapy is a very young field and has not yet resulted in any successful treatments.
Targeting Cancers For New Drug Therapies
Researchers at The Institute of Cancer Research reported in the journal Nature Reviews Drug Discovery that they have found a new way of rapidly prioritizing the best druggable targets online. They managed to identify 46 previously overlooked targets.
The researchers used the database together with a tool and were able to compare up to 500 drug targets in a matter of minutes. With this method, it is possible to analyze huge volumes of data to discover new drug targets, which can lead to the development of effective cancer medications.
The scientists analyzed 479 cancer genes to determine which ones were potential targets for medications. Their approach was effective – they found 46 new potentially “druggable” cancer proteins.