Breast Cancer Notes

These notes are from a lecture by Dr Claudine Isaacs, who co-directs the Breast Cancer Program at Georgetown University. If you know something on the subject and I got something wrong, please correct me! It’s amazing that I put these notes aside for about a week and already I am not certain that I understood what I thought I did!

The incidence of breast cancer has decreased in the past decade, but no one knows exactly why.

The role of hormones in breast cancer is still not fully understood, but estrogen is linked to breast cancer. The longer a woman has her menstrual cycle, the more likely she is to develop breast cancer. (a comment here: doesn’t this suck? not only does she have longer to deal with a monthly flow, she has a higher risk of cancer)

Does HRT raise the risk of breast cancer? It appears to. (Major Bummer)

The “breast cancer gene” is autosomal dominant, which means you can get it from either side, mother or father, don’t need both to manifest.

Breast cancer is much more common in the Western hemisphere than the Eastern hemisphere. Why? Noone knows. After Eastern women move to this hemisphere, their rate of breast cancer catches up to Westerners. (It must be some sort of environmental factor, right?)

Higher weight increases likelihood of breast cancer, mainly because estrogen is both produced and stored in fat.

Tight bras. Deodorant. Breast size. Taking the pill. Having an abortion. None of these are risk factors.

An important fact to know about your cancer: Is it Hormone receptor positive or not? Is it Her-2 positive or not? Being negative here is not a good thing.

Tamoxifen mimics estrogen, which is why it works to fight cancer. If you think of hormones as “lock and key”, tamoxifen fits into the reception just like estrogen does, but it does not cause the same chain of events that estrogen does.

Chemotherapy kills rapidly dividing cells, which is why it also causes hair to fall out, and the lining of the gut to have problems. 4 cycles of chemotherapy are a standard treatment.

The Baseline risk is different than the Absolute risk to the patient. You need to know the patient’s risk and then multiply times the baseline risk.

Endocrine therapy can be given to women at a high risk of breast cancer. Will this become more standard practice?

The newest thing is Biologic Therapy, when antibodies are directed at specific targets. Herceptin and others are on the front line here. Monochromal antibodies may prevent cancer from growing by shutting off the blood supply to the tumor.

Lifestyle interventions — can these reduce the risk of cancer recurrence? Yes. Exercise improves. Weight management. Reduced alcohol intake.

Metastatic breast cancer (spread to other organs or bone) is not curable. The treatment issue is about prolonging survival and quality of life.

We are probably going to hear more about Tamoxifen because it is also a good drug for osteoporosis. Some discussion about even using it prophylactically in some women.

Here’s what I’m still wondering about: Cancer cells themselves. I understand that they are evil because they replicate and proliferate at the expense of the larger organism. I also understand that they exist in all of us, or COULD exist. If chemotherapy will never kill 100% of cancer cells, perhaps killing these cells is not the point? Perhaps figuring out how to keep the cells from “switching on” and starting to replicate wildly is the point? Or is it just more possible to kill them?

Tomorrow night: Health and the Environment.


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