BREAST CANCER : RISK FACTORS

Breast Cancer is the most common cancer disease seen in developed countries and it is spreading like a wild fire in western hemisphere. The incidence has been progressively increasing , in  USA  in 1960 it was supposed to affect 1 out of every 20 women ,  and presently it is estimated to affect 1 out of every 8 women . The American Cancer Society predicts that 2, 11,000 new cases of breast cancer will be diagnosed in 2005 and will bring death warrant for about 43300 ladies.

In India, the incidence of breast cancer is not so high but it is definitely higher that what it was about 20 years back. If you take 100 female cancer patients then 16 of them are of breast cancer, and the estimation is that 1 out of 20 women will suffer from this disease during her life time. In contrast to developed countries, cancer cervix is the commonest cancer seen in females but this is fastly changing and lately it has been found that in metropolitan cities of Mumbai, Chennai, Delhi etc. breast cancer has overtaken the incidence of cancer cervix, a sign of modernization?
It is not widely known that breast cancer can also affect males, the incidence is very low; for every 100 female breast cancers, we can see one male patient. It should be also remembered that breast cancer in males have poorer prognosis because of smaller size of breast, which involves the underlying muscles and overlying skin quite early.
It should be remembered that because of its biological behaviour no two patients of breast cancer are the same and hence they do not behave in the same manner.

In spite of extensive research costing millions of dollars, the exact cause of breast cancer has not been established but clinical data have clearly shown a number of risk factors which may be responsible for the development of breast cancer. A brief review of these factors may be helpful in the prevention of the disease.

  1. Age:  The incidence is very low in the age group below 25 years and is seen more commonly after the age of 50 years. The disease is much more aggressive in younger patients.
  2. Sex:  The female sex clearly increases the risk by 99%.
  3. Menstrual Cycle: The disease is supposed to be much more common in the ladies who have a longer menstrual life, i.e. the onset of menstruation  is earlier (prior to the age of 12 years) and cessation of menstruation is later (after the age of 50 years).
  4. Marital and maternal status:  The disease is supposed to be much more common in ladies who have not got married, or if married then have not given birth to children, or if given birth to children then have not breast fed their off springs.
  5. Family History of Breast Cancer: A positive history of breast cancer in the immediate relations (mother, sisters, and daughters) increases the risk. The timing of development of breast cancer in the relative has some bearing on the risk factor, if the family member was post-menopausal (older lady) at the time she was diagnosed to have breast cancer then the lifetime risk is increased by 5%, if she was in premenopausal stage (younger person) the lifetime risk is increased by 18% and if the relation was in premenopausal stage with cancer in both the breasts then the lifetime risk jumps to an increase by 50%.
  6. One should clearly understand that the above figures do not show the absolute incidence of developing breast cancer but only indicate the lifetime   risk vis a vis other women who do not have positive family history.
  7. Smoking and alcohol intake:  Both these factors are supposed to increase the risk.
  8. Prior history of breast cancer:   Ladies with past history of having breast cancer on one side are at greater risk to develop cancer on the opposite side also, about 1 % per year and the lifetime risk is 10%.
  9. Obesity and higher intake of saturated fatty acids:  These have been also linked.
  10. Lethargy:  It has been said that a woman who exercises four hours per week reduces her risk of breast cancer. Exercise pumps up the immune system and cuts the estrogen (female hormone) level.
  11. Radiation to chest:  Exposure of breast to radiation as that may happen during radiotherapy for any cancer disease located either inside the chest or on the chest wall may make the person more vulnerable for the development of breast cancer. This may happen 10 to 12 years after the exposure.
  12. Oral Contraceptives: Ladies below the age of 35 years, who have been using oral contraceptive pills for more than 10 years, are at increased risk for development of breast cancer.
  13. Hormone Replacement Therapy :  Combined oestrogen plus progestin hormone therapy ( CHT ) after the cessation of menstruation used to be a common practice, and was supposed to be good for reducing the risk of osteoporosis, heart disease, colon cancer and Alzheimer’s disease.  But it has been shown that both, continuous and sequential uses of combined hormone therapy are linked with increased risk for development of breast cancer. Not only this, but it has been also found to be associated with diagnosis at a more advanced stage of breast cancer and a much higher rate of mammography abnormalities leading to anxiety and subsequent costly workup like stereo tactic or mammotome biopsy.

The researchers also found that the women who have been using only Oestrogen therapy as hormone replacement therapy   (i.e., not combining with progestin) for 25 years or longer had no significant increase in risk of breast cancer.

Risk factors for male breast cancer:

As mentioned earlier, males can also develop cancer in their breasts although the incidence is very low. The risk factors in males include hormonal abnormality, presence of gynaecomastia ( presence of exceeesive breast tissue in males ) , intake of hormone containing drugs like oestrogen, history of trauma or infection to  the testis etc.
I shall like to caution the readers that the above mentioned facts have been derived from the statistical analysis of the factors seen in the cancer breast patients; they should not be taken as causative or predisposing factors. In the present era when cancer breast has become such a common disease, it is advisable to follow the guide lines.