Melanoma of the skin

5 Most Common Cancers

From the perspective of the longevity, cancer is the enemy of humanity (at least until we learn to use some of the processes by which it developes and prospers to our benefit). You know what they say – you need to know your enemy. Read the article to find out what are the most common cancers.

Cancer – introduction.

Cancer is a class of diseases characterized by an uncontrolled growth and spread of cells. Cancer may be either hereditary (5-10% of all cancers) or caused by other factors (remaining 90-95%). While there may be many different factors leading ultimately to the development of cancer, every single cancer involves the malfunction of genes controlling growth and division of cells. When a hereditary cancer is involved, the condition results from an inherited genetic alteration. Such a genetic setup carries a high risk of developing a specific type of cancer.

Hereditary cancers often occur earlier than the sporadic form of the same cancer (non-hereditary cancer is called sporadic cancer), which is the reason why people with the history of hereditary cancers in the family are advised to undergo screenings at a younger age. Some of the most common types of hereditary cancers include: breast cancer, ovarian cancer, prostate cancer and colorectal cancer. Anyone with a family history of these types of cancers should seek genetic counseling.

Non-hereditary genetic damage leading to cancer may result from internal or external factors. Internal factors include (but are not limited to): hormones, metabolism of nutrients within cells and immune conditions. Some of the external factors are: use of tobacco, excessive exposure to sunlight, exposure to chemicals, radiation and infectious organisms. Lifetime cancer risk is also affected by poor diet, obesity and lack of physical activity.

Cancer is most commonly diagnosed in people who are middle-aged or older – 78% of those affected are 55 or older. However, cancers also affect children – about 14 out of every 100,000 in the U.S. each year. Childhood cancers may appear suddenly, without any early symptoms. They look different from adult cancers under a microscope, respond differently to treatments and have a relatively high cure rate (not always and not all of them). Cancer, however, is still a second-leading cause of death among children between 1 and 14 (accidents being the first).

Cancers are commonly treated with chemotherapy, hormone therapy, biological therapy, targeted therapy, radiation and surgery. The branch of medicine dealing with tumors and cancers is called oncology. Tumor is not synonymous with cancer. Cancer is malignant by definition. Tumor can be malignant, pre-malignant, or benign. Tumor can also have no cancerous potential at all. Lifetime risk of developing a cancer stands at about 45% for males and about 37% for females (for the United States). The 5-year survival rate for people diagnosed with cancer between 1999 and 2006 is 68%. In 2011, approximately 570,000 people are expected to die of cancer in the U.S. (or about 1,500 a day), making it the second most common cause of death in the country, after a heart disease.

What are the most common cancers? Below are the leading sites of new cancer cases.

Melanoma of the skin
Melanoma of the skin
Source: National Cancer Institute

5) Melanoma of the skin (Males)

40,000 new cases (5% of all newly diagnosed cancers in males)

This cancer develops in the melanocytes – or the pigment cells in the skin (melanocytes, however, are also present in other parts of the body, like the bowel or eye). Melanoma can be very dangerous, because it may spread to other parts of the body. The excessive exposure to sunlight significantly increases the risk of developing melanoma of the skin. When melanoma is detected early, it can be removed with a relatively simple surgery. It is therefore important that people seek medical consultation upon discovering unusual spots on the skin. 5-year relative survival rate is 91%.

Thyroid (Females)

36,550 (5%)

This is a malignant thyroid neoplasm. The most common symptom is a lump in the neck. Pain in the neck, difficulty breathing or swallowing, swollen lymph nodes and persistent pain in the neck and throat are some of the other common symptoms of thyroid cancer. Radiation exposure from medical treatment or from nuclear fallout is one of the risk factors. Most cases are highly curable, with surgery (total removal of thyroid gland – thyroidectomy) being the first choice of treatment. 5-year relative survival rate for all patients is 97%.

Histopathology of urothelial carcinoma of the urinary bladder.
Histopathology of urothelial carcinoma of the urinary bladder.

4) Urinary bladder (Males)

52,020 (6%)

Urinary bladder cancer is one of the several types of malignant growths of the urinary bladder. Blood in the urine is the most common symptom. Other symptoms include increased frequency of urination and irritation during urination. Smoking is the most critical risk factor for bladder cancer. Other significant risk factor is living in the area with high levels of arsenic in drinking water. Surgery is used in over 90% of all cases, and 5-year relative survival rate is 80%.

Micrograph of endometrioid endometrial adenocarcinoma, the most common form of endometrial cancer.
Micrograph of endometrioid endometrial adenocarcinoma, the most common form of endometrial cancer.

Uterine corpus (Females)

46,470 (6%)

This is the most common gynecological cancer. It affects the body of the uterus and usually occurs in the endometrium (the lining of the uterus). It is expected to kill over 8,100 women in 2011. Symptoms include abnormal spotting or bleeding and pain during urination and intercourse. Most significant risk factors are obesity and increased estrogen exposure (for example from menopausal estrogen therapy, never having children, late menopause, Lynch syndrome, diabetes, or a history of polycystic ovary syndrome). Pregnancy, oral contraceptives and physical activity all provide protection against endometrial cancer. Treatments include surgery, chemotherapy, radiation and hormones. The 5-year relative survival rate is 83%.

Histopathologic image of colonic carcinoid stained by hematoxylin and eosin.
Histopathologic image of colonic carcinoid stained by hematoxylin and eosin.

3) Colon & rectum (Males, Females)

71,850 (9%) (Males); 69,360 (9%) (Females)

This is the third most common cancer for both women and men. It’s going to kill 49,380 people in 2011. Colorectal cancer shows no symptoms at an early stage, and therefore screening is necessary to detect it. In late stages – rectal bleeding, blood in the stool and cramping pain in the lower abdomen may appear. It is also possible for blood loss caused by this cancer to lead to anemia (low red blood cells), manifesting itself with weakness and fatigue. Risks include: age over 50 years, obesity, physical inactivity, eating processed meat, alcohol consumption and smoking. Screening is recommended for men and women over 50 years of age. Surgical removal is the most common treatment, and is supported with chemotherapy and radiation if the cancer has spread. Permanent colostomy is rarely needed. 5-year relative survival rate is 65%.

Histopathologic image of small cell carcinoma of the lung.
Histopathologic image of small cell carcinoma of the lung.

2) Lung & bronchus (Males, Females)

115,060 (14%) (Males); 106,070 (14%) (Females)

Lung cancer accounts for more deaths than any other cancer for both men and women. It will kill 156,940 people in 2011. Symptoms include: persistent cough, chest pain, voice change, recurrent pneumonia or bronchitis and blood in sputum. The biggest risk factor is very obvious – cigarette smoking. Other risks are: exposure to secondhand smoke and certain substances (arsenic, radon, cadmium, asbestos, chromium), radiation, air pollution and a history of tuberculosis. Treatment includes surgery, targeted therapy, radiation therapy and chemotherapy. 5-year survival rate for all stages combined is only 16%.

Micrograph showing prostatic acinar adenocarcinoma (the most common form of prostate cancer).
Micrograph showing prostatic acinar adenocarcinoma (the most common form of prostate cancer).

1) Prostate (Males)

240,890 (29%)

This is the most common cancer in men, and a second one in terms of cancer deaths in men. Early stage usually has no symptoms. Advanced stages may cause interrupted urine flow, inability to urinate, difficulty starting or stopping urination, frequent need to urinate and pain or burning sensation during urination. Since advanced stages often spread to the bones, pain in the spine, ribs or hips may also be a symptom. Age (97% of cases in men over 50 years old, 62% – 65 years old and older), race (incidence rates are higher in African Americans than in whites) and family history are the most significant risk factors. Obesity and smoking increase the risk of dying from prostate cancer. Treatment options vary depending on stage, grade of cancer and age, and include surgery, radiation (external or radioactive seed implants) and hormone therapy. 5-year relative survival rate for all stages combined is 99.6%.

Normal (left) versus cancerous (right) mammography image.
Normal (left) versus cancerous (right) mammography image.

Breast (Females)

230,480 (30%)

Breast cancer will kill 39,520 women in 2011 (and 450 men). It’s a second cause of cancer deaths in women (lung cancer being the first). Abnormality detected during mammography is often the earliest sign of breast cancer. This shows the importance of screening, since many people mistakenly assume that a small lump in the breast is the first detectable symptom. Mammography may detect changes before they can be felt as a painless mass – and time is important, as with all cancers. Other symptoms include changes to the breast (distortion, thickening, tenderness, irritation, redness) or the nipple (retraction, ulceration, spontaneous discharge). Risk factors include: age, obesity, use of combined progestin and estrogen hormone therapy, lack of physical activity, alcohol consumption, family history of breast cancer, high breast tissue density, high dose of radiation to the chest, never having children, having first child after the age of 30, recent use of oral contraceptives. Most common treatments are lumpectomy (removal of the tumor) and mastectomy (removal of the breast), chemotherapy, radiation therapy, hormone therapy and targeted therapy. 5-year relative survival rate is 90%.

Source for images: National Cancer Institute

Further reading

MedlinePlus – Colon cancer – Colorectal cancer
WebMD – Breast Cancer Health Center
National Cancer Institute page on breast cancer
National Cancer Institute page on prostate cancer
WebMD – Prostate Cancer Health Center
Prostate Cancer Foundation