When cancer develops from the epithelial lining of external or internal organs, it is known as a carcinoma.
In general, patients with a carcinoma have fatigue, tiredness, anemia and weight loss. The weight loss can be quite pronounced and rapid. The specific symptoms of a carcinoma depend on where it is located; for instance, a skin cancer, may present the darkening of skin, itching or minor bleeding. A carcinoma of the pancreas may present with abdominal or back pain, nausea and jaundice.
Other symptoms may include: Thickening of the breast skin Rash or redness of the breast Swelling in one breast New pain in one breast Dimpling around the nipple or on breast skin Nipple pain, nipple turning inward, or nipple discharge Lumps in underarm [webmd.com]
A small number of women are diagnosed with DCIS after finding a lump or experiencing nipple discharge or, occasionally, a change in the nipple itself. [cancernz.org.nz]
In general, when a cancer is suspected, the following work up is necessary.
- Complete blood count
- Electrolyte levels
- Renal and liver function
- Urine analysis
- Coagulation profile
- Biopsy of the lesion
Only a few carcinomas have specific tumor makers  which include:
- Ovary (CA 125)
- Pancreas (CA 19.9)
- Liver (alpha fetoprotein)
- Colon cancer (CEA)
- Lung cancer (EGFR)
- Prostate cancer (PSA)
Other tests depend on where the cancer is located. A CT scan and/or MRI is usually obtained to determine the extent and location of the cancer.
Once a cancer has been biopsied, its grade is determined by the pathologist. All patients who have a cancer are staged according to tumor size location, regional and distant lymph nodes involvement and other areas where the tumor may have spread. No treatment should be started until the staging is confirmed.
The TNM system is a universal method to stage cancers. This staging system is accepted by the American Joint Committee on Cancer and the Union for International Cancer Control (UICC). The TNM system is based on the size and extent of the primary cancer (t), the number of lymph nodes involved (N) and the presence of metastases (M). A number is added to each letter to indicate the extent and size of primary cancer and the extent of spread.
Primary tumor (T)
- TX: Primary tumor cannot be determined
- T0: No evidence of primary tumor
- Tis: Carcinoma in situ (CIS; abnormal cells are present but have not spread to neighboring tissue; although not cancer, CIS may become cancer and is sometimes called preinvasive cancer)
- T1, T2, T3, T4: Size and/or extent of the primary tumor
Regional lymph nodes (N)
- NX: Regional lymph nodes cannot be evaluated
- N0: No regional lymph node involvement
- N1, N2, N3: Degree of regional lymph node involvement (number and location of lymph nodes)
Distant metastasis (M)
- MX: Distant metastasis cannot be evaluated
- M0: No distant metastasis
- M1: Distant metastasis is present
For example, lung cancer classified as T3 N2 M0 refers to a large tumor that has spread outside the lung to nearby hilar lymph nodes but not to other parts of the body. Colon cancer T2 N0 M0 means that the tumor is located only in the colon and has not spread to the lymph nodes or any other part of the body.
The treatment of a cancer depends on the type, stage and patient status. The classical treatments for cancer include surgical resection, chemotherapy, radiation, hormonal therapy, immunotherapy and use of biological agents. In the last decade, the development of biological agents that targer the immune system rather than cancer cells seems to have had a small impact on disease free survival . There are also plan to use certain vaccines to prevent cancer .
The prognosis depends on the type of cancer, the location as well as the stage and grade of the cancer. Other factors that affect prognosis include age of patient, physical status of the individual and how the cancer cells respond to treatment. The higher the stage, the worse the prognosis. It is important to note that just because patient's have advanced cancer does not mean that they do not require treatment. Many of these patients benefit from palliative care and pain control.
Different types of carcinomas have their own etiological factors. In general, it is estimated that nearly one third of cancers globally are due to potentially modifiable risk factors which include the use of tobacco, alcohol consumption and a diet that is low in vegetables and fruits. One very common cause of skin cancers is sunlight. Solar radiation has been linked to actinic keratosis, squamous cell and basal cell cancers . In addition, being obese and having acquired a sexually transmitted infection (eg. Human papillomavirus (HPV) infection) also appear to be risk factors for cancers (eg. cervical cancer) .
Hence, many countries are now trying to introduce steps to help the public reverse these modifiable risk factors. Vaccination against hepatitis B and HPV is now commonly performed in most countries to prevent liver and cervical cancers . Finally, obesity has been linked to several cancers such as lung, colon, breast, kidney and uterus. it is believed that foods high in glycemic index may promote cancers .
Cancer is the second leading cause of death in many western countries, lagging just behind heart disease. The cancer with the highest mortality is that of the lungs. The most common cancer occurring in men is prostate whereas in women, breast cancer is most common. In children, leukemia appears to be the most common malignancy. Cancer is a major public health problem globally and carries a high burden on society. Even when the patients of cancer survive, there is a high risk of developing recurrence.
The exact molecular mechanism that explains cancer development is not known; however, the most widely held theory is that there are one or more mutations of genes leading to damage to the DNA. The genetic mutations transform normal cells into a cancer cell; which multiply repeatedly and unchecked. The genetic mutations may also include activation of oncogenes and inactivation of tumor suppressor genes. There are some individuals who have a genetic predisposition to cancer due of inheritance of mutated genes. While models of carcinogenesis are simplistic in nature, carcinogenesis in reality is a complex phenomenon which requires a constellation of steps that take place over a long period of time.
The subtypes of carcinoma include the following:
- Carcinoma-in-situ is the earliest form of cancer that does not penetrate beyond the epithelium of the organ and has hence not spread either locally or systemically.
- Adenocarcinoma is a type of carcinoma that evolves in glandular tissue.
- Squamous cell is a type of carcinoma originating from squamous cells which form the superficial external layers of skin or the epidermis. These flat cells make keratin that is a major component of hair, skin and nails.
- Adenosquamous cell carcinoma is a type of carcinoma with features of both a squamous cell and adenocarcinoma.
- Anaplastic or undifferentiated carcinoma is a type of cancer containing cells that are primitive or lacking in distinct cytological features. A common example is anaplastic thyroid carcinoma.
- Basal cell carcinoma is a type of skin cancer that starts in the basal cells of the skin that normally function to replace old skin cells.
- Carcinosarcoma is a combination of a sarcoma and a carcinoma. These cancers may occur in connective tissue.
- Clear cell carcinoma is one in which cancer cells are clear. A classic example is renal cell cancer.
- Invasive carcinoma or infiltrating carcinoma is a cancer that has spread to adjacent organs.
- Large cell carcinoma is a carcinoma with large cells that are often polygonal in shape. A classic example is a large cell cancer of the lung that primarily involves the bronchioles.
- Non-invasive carcinoma is one which has not invaded any adjacent tissue and is localized at the site of occurrence.
- Pleomorphic carcinoma is one with spindle or giant cell features. It may also have features of squamous cell and adenocarcinoma combined. Pleomorphic carcinoma occurs in the parotid gland.
- Small cell carcinoma is a carcinoma with small cells and scanty cytoplasm. A classic example is small cell lung cancer, which is very aggressive and usually spread at the time of diagnosis.
- Spindle cell carcinoma is one with cells that are slender at both ends and mimic cancers of connective tissues. Spindle cell cancers occur in muscle, gastrointestinal tract and connective tissue.
One should discontinue smoking, maintain a healthy weight, eat ample fruits and vegetables, exercise regularly and avoid excess alcohol to prevent most types of cancer . It is vital to encourage patients to avoid weight gain as this is also a significant risk factor for some cancers. Safe sex, avoid sharing needles and use of sunscreens are some preventive measures that can be undertaken to avoid cancers.
The majority of cancers that develop in humans are carcinomas. Carcinoma is any cancer that develops from the outer or inner epithelium of an organ. All organs that have an epithelial lining have the potential to develop a carcinoma; for instance, a squamous cell cancer may occur on the surface of the skin. Besides skin, epithelial lining is present in almost all internal organs and passageways like the respiratory tract, gastrointestinal tract and the urinary tract.
Adenocarcinomas generally occur in endocrine and mucus secreting organs like the pancreas, colon, prostate, breast, lung, liver, kidney, etc. These cancers often present as thickened white plaque and because of the surrounding soft tissue, they are often very invasive locally. This propensity to invade locally often prevents them from being cured by surgical resection. Similarly squamous cell cancer can occur in many organs besides the skin like the bladder, oral cavity, vagina, and anal canal.
Carcinoma is a form of cancer that derives from epithelial cells. People should be educated that some cancers are preventable. In order to prevent cancer, one must change the lifestyle and eat a healthy diet, exercise regularly, discontinue or avoid smoking and drink alcohol in moderation. The diet should consist of plenty of vegetables and fruits, limited amount of fat, and plenty of fiber. It is important to avoid weight gain because obesity has been linked to cancers of the breast, colon, lung, prostate and kidney. One should try and walk at least 1 hour a day 5-6 times a week. To protect from the sun, one should avoid the midday sun, wear appropriate garments, avoid tanning salons and use sunscreens liberally when going out. It is important to get vaccinated against hepatitis B and human papilloma virus as this has been shown to prevent liver and cervical cancers. Finally, one should avoid risky behavior (like sharing needles that may transmit HIV) and practice safe sex.
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