Risk factors for cancer can be categorized in two groups: lifestyle choices that can be changed and inherited traits that cannot be changed. Risk factors that can not be changed include age, sex, and family history. Risk factors that can be changed include use of tobacco or alcohol, eating habits, and exposure to the sun.
Different types of cancer have different risk factors. Individuals with an increased risk of cancer should be screened earlier and more often than those who are at average risk for cancer. It is highly recommended that both men and women work with their family doctor to develop a plan for assessing the risk for various types of cancer.
Below are some common types of cancer and their risk factors:
Over the course of a lifetime, one in eight women will be diagnosed with breast cancer.
Risk factors you cannot change include:
- Age and gender: the risk of developing breast cancer increases with age. The majority of advanced breast cancer cases are found in women over age 50. Women are 100 times more likely to get breast cancer than men.
- Family history of breast cancer: a woman may also have a higher risk for breast cancer if she have a close relative who has had breast, uterine, ovarian, or colon cancer. About 20 - 30% of women with breast cancer have a family history of the disease.
- Genes: some individuals have genes that make them more prone to developing breast cancer. The most common gene defects are found in the BRCA1 and BRCA2 genes. These genes normally produce proteins that protect you from cancer. If a parent passes a defective gene, there is an increased risk for breast cancer. Women with one of these defects have up to an 80% chance of getting breast cancer some time during their life.
- Menstrual cycle: women who get their periods early (before age 12) or went through menopause late (after age 55) have an increased risk for breast cancer.
Other risk factors include:
- Alcohol use: drinking more than 1 - 2 glasses of alcohol a day may increase your risk for breast cancer.
- Childbirth: women who have never had children or who had them only after age 30 have an increased risk for breast cancer. Being pregnant more than once or becoming pregnant at an early age reduces your risk of breast cancer.
- DES: women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer after age 40. This drug was given to women in the 1940s - 1960s.
- Hormone replacement therapy (HRT): there is a higher risk for breast cancer if a woman received hormone replacement therapy for several years or more. Many women take HRT to reduce the symptoms of menopause.
- Radiation: if an individual received radiation therapy as a child or young adult to treat cancer of the chest area, they have a significantly higher risk of developing breast cancer.
Breast implants, using antiperspirants, and wearing underwire bras do not raise risk for breast cancer.
Almost all cervical cancers are caused by HPV (human papillomavirus). HPV is a common virus that is spread through sexual intercourse. There are many different types of HPV. Some strains lead to cervical cancer. (Other strains may cause genital warts, while others do not cause any problems at all.)
Other risk factors for cervical cancer include:
- Having sex at an early age
- Multiple sexual partners
- Sexual partners who have multiple partners or who participate in high-risk sexual activities
- Women whose mothers took the drug DES (diethylstilbestrol) during pregnancy in the early 1960s to prevent miscarriage
People who are at higher risk include:
- African-American men, who are also likely to develop cancer at every age
- Men who are older than 60
- Men who have a father or brother with prostate cancer
Other people at risk include:
- Men exposed to agent orange exposure
- Men who abuse alcohol
- Men who have been exposed to cadmium
A common problem in almost all men as they grow older is an enlarged prostate (benign prostatic hyperplasia, or BPH). This problem does not raise your risk of prostate cancer.
Skin cancer is the most common form of cancer in the United States. Known risk factors for skin cancer include the following:
- Complexion: skin cancers are more common in people with light-colored skin, hair, and eyes.
- Genetics: having a family history of melanoma increases the risk of developing this cancer.
- Age: non-melanoma skin cancers are more common after age 40.
- Sun exposure and sunburn: most skin cancers occur on areas of the skin that are regularly exposed to sunlight or other ultraviolet radiation. This is considered the primary cause of all skin cancers.
Skin cancer can develop in anyone, not only people with these risk factors. Young, healthy people, even those with dark skin, hair, and eyes, can develop skin cancer.
The exact cause of testicular cancer is unknown. There is no link between vasectomy and testicular cancer. Factors that may increase a man's risk for testicular cancer include:
- Abnormal testicle development
- History of testicular cancer
- History of undescended testicle
- Klinefelter syndrome
Other possible causes include exposure to certain chemicals and HIV infection. A family history of testicular cancer may also increase risk.
Testicular cancer is the most common form of cancer in men between the ages of 15 and 35. It can occur in older men, and rarely, in younger boys.
White men are more likely than African-American and Asian-American men to develop this type of cancer.
Most cases of endometrial cancer occur between the ages of 60 and 70 years, but a few cases may occur before age 40.
The following increase your risk of endometrial cancer:
- Estrogen replacement therapy without the use of progesterone
- History of endometrial polyps or other benign growths of the uterine lining
- Infertility (inability to become pregnant)
- Infrequent periods
- Tamoxifen, a drug for breast cancer treatment
- Never being pregnant
- Polycystic ovarian syndrome (PCOS)
- Starting menstruation at an early age (before age 12)
- Starting menopause after age 50
Associated conditions include the following:
- Colon or breast cancer
- Gallbladder disease
- High blood pressure
- Polycystic ovarian disease