Obviously, as he also mentioned, it’s a different biologic background of hormones in a male vs. a female patient. There’s reason to think that some of those treatments could differ. In general, the subtypes are a little bit different. We see very, very few cases of triple-negative breast cancer in men. I think I’ve seen only one or two in my career. The ones I remember were probably radiation induced. They were cancer survivors who’d had chest-wall radiation for previous diseases. Those patients are very uncommon.
We also tend to see that the histology patterns are a little bit different. We tend to see more ductal cancers in men than we do in women as a relative proportion.
One thing that I always try to remember is that the risk for BRCA mutations or underlying germline genetic mutations is higher in men than in women. Just having a diagnosis of male breast cancer is an indication to consider genetic testing or meet with a genetic counselor to look for a BRCA1 or BRCA2 mutation.
Now, most men will not have that. Only roughly 10% of male patients, or maybe a little less, will have a BRCA2 mutation; for BRCA1, it’s more like only 1% or 2%. They’re not that common. Certainly, male breast cancer is recognized as being associated with the BRCA mutations.
Dr. Cardoso: If I have to give a take-home message in terms of biology, it would be that if there is a diagnosis of hormone receptor–negative or HER2-positive disease in a male patient, I would ask for a confirmation of the diagnosis. It’s not that it cannot exist, but it’s so rare that it’s worthwhile to confirm.
You mentioned that triple-negative disease is less than 1%, at about 0.5%, and HER2-positive disease is about 9%-10%. I think it will be very important to keep this in mind and confirm the biology if you have a different diagnosis than ER-positive, HER2-negative. Unfortunately, I received some cases where this was not done, and in fact, it ended up being a technical problem. People can receive the wrong treatment based on that.
Dr. Giordano: I’ve also seen that happen when it’s a metastasis to the breast rather than a primary breast cancer. I completely agree. That’s an excellent point.
Management approaches
Dr. Cardoso: Let’s go now to management and focus on early breast cancer first. Sharon, what are your main take-home messages for a professional who doesn’t see this very often? What does someone need to remember when they manage a male patient who has early breast cancer?
Dr. Giordano: In general, in terms of chemotherapy, we essentially use the same guidelines as we do for women. Most of the male patients will have tumors that are hormone receptor positive. For endocrine therapy, we typically rely on tamoxifen as the standard of care for adjuvant endocrine treatment for breast cancer.
There are some data suggesting that there can be some efficacy of aromatase inhibitors as single agents. In general, and extrapolated from some population-based registry data, the outcomes for men treated with single-agent aromatase inhibitors don’t tend to be as good as for those treated with tamoxifen.
I know that these are not randomized data so there are all the caveats of that, but the best information we have suggests that tamoxifen appears to likely be more effective. Typically, we stay with tamoxifen. If, for some reason, a man cannot tolerate tamoxifen or has a contraindication, then we could use a GnRH agonist along with an aromatase inhibitor.