Based on the strength of scientific literature, the following are the risk factors for the different types of cancer which are prevalent in Tanzania: –
Cancer of Cervix
The risk factors are infection with Human Papilloma Viruses (HPV), early age at first sexual intercourse, many sexual partners or partners who have had many sexual partners, multiple births, long-term oral contraceptive use, and cigarette smoking.
Kaposi’s sarcoma
The main risk factor is infection with Human Immunodeficiency Virus (HIV). Other risk factors include, being a male and having multiple sexual partners.
Cancer of Oesophagus
The most important risk factors are tobacco use and excessive alcohol ingestion. Other possible
risk factors include obesity, inadequate diet, poor nutrition, decreased levels of certain nutrients (e.g. carotene, ascorbic acid, riboflavin, niacin, thiamine, zinc, magnesium, and selenium), and insufficient consumption of fruits and vegetables.
Breast Cancer
The risk factors are family history (especially mother or sister) of breast cancer, personal history of breast, ovarian, or endometrial cancer, susceptibility genes (BRCA-1, BRCA-2), some forms of benign breast disease (atypical hyperplasia), menstruation at an early age, late menopause, never bearing children, first child born after age 30, high doses of ionizing radiation, long term use of post-menopause estrogens and progestin, obesity after menopause, and excessive alcohol consumption. Other possible risk factors are dietary fat and physical inactivity.
Cancers of Head & Neck
Tobacco and alcohol usage account for most head & neck cancers. Another risk factor is a diet low in fruits and vegetables. Other possible risk factors are poor oral hygiene, trauma and use of mouthwashes with high alcohol content.
Non-Hodgkin Lymphoma
Risk factors are reduced immune function particularly due to infection with HIV, Epstein-Barr or human T-cell leukaemia/ lymphoma virus. Possible risk factors are organ transplant, occupational exposure to pesticides, herbicides, or organic solvents.
Hodgkin Lymphoma
Risk factors are infectious mononucleosis and Epstein-Barr virus infection. Possible risk factors are family history of Hodgkin lymphoma especially among siblings and genetic factors.
Skin Cancer
Majority of the patients with skin cancers in Tanzania are albinos. The risk factors are ultraviolet radiation (sunlight), fair skin, high doses of ionizing radiation, occupational exposure to arsenic, polycyclic hydrocarbons (coal tars, pitches, and asphalt, creosote, soot, lubricating and cutting oils) and National Cancer Control Strategy (NCCS) – (2013-2022). rare hereditary diseases such as multiple basal cell carcinoma syndrome, xeroderma pigmentosum, and albinism. Possible risk factors are burn scars, chronic infections, and photosensitizers in tanning, cosmetics, and medicines.
Bladder Carcinoma
The most important risk factor is bladder infection with schistosoma haematobium (parasitic flatworm) and cigarette smoking; other risk factors are occupational exposure to benzidine and 2-naphthylamine and occupations in the dye, leather or rubber industry. Possible risk factors are heavy coffee consumption, urinary tract infections or low urine flow, dietary factors, tobacco use and genetic factors.
Leukaemia
The risk factors are family history, high doses of ionizing radiation, alkylating drugs used to treat cancer and other diseases, and occupational exposure to benzene. Possible risk factors are exposure to electromagnetic fields, pesticides, smoking, and several immune-related diseases. The risk factors for other cancers observed at ORCI, although not so frequently: –
Liver
The risk factors are chronic infection with hepatitis B or C virus, cirrhosis of the liver (chronic liver injury, usually due to alcohol abuse), aflatoxin ingestion (produced by a common mold that invades poorly stored peanuts and other foods), and occupational exposure to thorium dioxide or vinyl chloride.
Lung
Tobacco smoking is responsible for nearly 90% of all lung cancers. Other contributing risk factors are environmental tobacco smoke (second-hand smoke). High doses of ionizing radiation, residential radon exposure and occupational exposure to mustard gas, chloromethyl ethers, inorganic arsenic, chromium, nickel, vinyl chloride, radon, asbestos or by-products of fossil fuel are also thought to increase risk. Possible risk factors are air pollution and insufficient consumption of fruits and vegetables.
Larynx
Most cases are caused by cigarette smoking. Other risk factors are alcohol and occupational exposure to asbestos.
Prostate
Risk factors are some types of prostatic hyperplasia and a family history, especially a father or brother. Possible risk factors are a diet high in animal fat, obesity, hormonal factors, a sexually transmitted agent, smoking, alcohol, and physical inactivity