Re: What is it about female breast tissue that makes it so prone to cancer?

Question: What is it about female breast tissue that makes it so prone to cancer?

Dear Marcela,

I'm afraid that the answer to your question is that we don't know. I could write you a page on theories that attempt to explain why breast cancer, and other cancers, occur. However, I'm not going to because it would lead you to think that we actually understand exactly what cancer is about. We have lots of ideas for what may be the causes of cancer, including viral infections, bad diet, menopause, chemicals, radiation and inherited genetic defects. Although we have a rough idea about what may cause cancer we still don't understand why certain tissues are affected more than others. All we really know is that cells grow uncontrollably and produce a mass of cells (tumour). It is the generally accepted theory that cells grow out of control after two or more genes mutate, leading to uncontrollable cell division; but this again is a theory. We know that cancer cells break off from the primary tumour (called metastases), enter the bloodstream and may form secondary tumours at different sites in the body. However, we don't know why breast cancer tends to metastasise to the lungs and brain, or why very few metastases are seen in the spleen or thymus (in any types of cancer).

As you can see this is not pleasant reading. The basic biological principles behind cancer, although anatomically well understood, are still very poorly understood at the cellular and molecular level, and this is why cancer is still such a devastating disease.

I have included underneath my reasons for why breast tissue is more susceptible to cancer than other tissues. I will emphasise that this is my opinion and others may disagree with what I say. I will refer you to www.healthgate.com which contains information on cancer and also provides access to search the scientific literature.

The most likely explanation for breast tissue being prone to cancer is the natural function of the cells of the breast. During pregnancy breast cells are "switched on" by the sex hormones, which causes them to divide and produce milk. Cancer occurs due to mutations in cell division controlling genes, which leads to the cells dividing uncontrollably. Therefore, because breast cells are already being switched on and off by the sex hormones, there is perhaps more chance of this control going wrong. This explains why men rarely get breast cancer (because their breast cells are not "switched on and off") and why areas of the female body that are not subject to sex hormone regulation have the same cancer incidence in men as in women ("Cancer Biology" by Raymond W. Ruddon, 3rd edition. Oxford University Press, 1995).

I hope this has answered your question.

Chris Ward