In this article, we address a question which most women with breast cancer and their loved ones have – why did the cancer occur? This continues our series of articles during October, which is observed as breast cancer awareness month.

At the time of diagnosis of breast cancer, the primary focus of a woman and her family is usually on understanding the prognosis and treatment.

Questions on prognosis include – Is my cancer curable? What is the stage of my cancer? What are the chances of a complete cure? Will I be completely normal after treatment?

Treatment-related questions include – What are the surgical options – can I preserve my breast or does it need to be removed? Will I need chemotherapy – what will be the side effects? How long will treatment last? How much will everything cost? Can I continue to work during treatment?

But sooner or later, the question which always surfaces is – Why did I get breast cancer? Is it something I did? Or something I didn’t do? Could I have done something to prevent it?

So, why does someone get breast cancer?

In many diseases we can pinpoint a cause (or “etiology”) – the tuberculosis bacterium causes TB, or a fall causes a hip fracture. However, cancer occurrence is not a cause-and-effect phenomenon. Rather than “causes”, we talk about “risk factors” for cancers, including breast cancer. This means that when someone has a particular risk factor for cancer, their chance of developing cancer is higher when compared to someone who doesn’t have that risk factor. Women with no risk factors can and do get breast cancer, and many women with several risk factors never develop breast cancer.

There are several risk factors associated with an increased risk of getting breast cancer. In a small fraction (presence of certain genetic mutations), the risk of developing breast cancer is high enough that it may warrant intervention (see this article on Angelina Jolie’s decision to undergo double mastectomy).

However, in the vast majority of women, even when they have a particular risk factor for breast cancer, the increase in their risk is very small (see this article on the estimation of cancer risk).

Being a woman itself is a risk factor for developing breast cancer (about 1% of breast cancers occur in men). Also increasing age increases the risk of developing breast cancer. Both these factors (being a woman and becoming older) are non-modifiable factors – that is we have no control over them. Other factors include younger age at puberty, older age at menopause, late age at first childbirth, and having a close relative with breast cancer. Again, the increase in risk in the presence of these factors is quite small, and many of these factors may not be under our control.

But there are quite a few risk factors that we can control. These include obesity, prolonged use of hormone replacement therapy following menopause, smoking, and excess alcohol consumption. The right lifestyle choices can significantly reduce our chances of developing breast cancer, in addition to preventing many other cancers as well.

In my personal practice, the overwhelming majority of women with breast cancer have no identifiable risk factor. When they ask me why they got breast cancer, all I can say is that science and medicine have no answer at present. I observe that many find comfort when they seek the answer in philosophy and spirituality.

To summarize, most women who develop breast cancer have no known cause. In a few, we can identify the presence of risk factors, some of which can be modified.