Pre- vs. Postmenopausal Breast Cancer Risk: There’s a Difference, But Does It Matter?

You’ve probably seen those plastic breast self-exam cards you hang on your showerhead as a reminder to feel for lumps on a monthly basis. I have one myself, and would read it over and over when I was trying to decide whether my lump was worrisome, reviewing the “reduce your risk” tips the card offered.

However, there are two points that I wasn’t aware of at the time that I was diagnosed: (1) we know little about causal factors, as most studies that examine risk are only correlational; and (2) there’s a difference between being premenopausal vs. postmenopausal when talking about breast cancer.

Okay, there’s a third one too: (3) risk factors don’t mean squat when I’m talking about my personal diagnosis.

First, a well-known fact: postmenopausal women make up the majority (approximately 2/3) of these cancer cases, so it’s not surprising that the focus is on them.

I, however, was premenopausal when I felt the lump in my left breast.

Imagine my surprise, then, when I learned that while being overweight or obese is a significant risk factor for postmenopausal women, being overweight as a premenopausal woman seems to offer protection against the disease. Whereas I thought I didn’t have any risk factors for breast cancer, as suggested by that plastic card in my shower, perhaps I did.

There’s not much talk about that protective element of weight for premenopausal women. You would be hard-pressed to find a popular website that mentions it. And no doctor would encourage a premenopausal woman to carry extra weight on the off chance that it might lower her risk of breast cancer; it’s too much of a liability for other health issues, including other cancers.

This explains why, if you’ve gone to a gathering of newly-diagnosed breast cancer patients, you’ll see some younger, remarkably fit women looking a little dazed and wondering what they’re doing there.

The weight risk factor is often posed in the following way (from the Mayo Clinic site): “Overweight and obese women have a higher risk of being diagnosed with breast cancer compared to women who maintain a healthy weight, especially after menopause.” Well, that’s not wrong, but it doesn’t tell the entire story.

Harvard Health Online puts it differently, with a caveat: “Being overweight or obese has been linked to breast cancer risk, especially for women after menopause, but the relationship is complicated. It may be that risk is increased in women who gain weight in adulthood but not in those who’ve been overweight since childhood.” That seems even more confusing and less reassuring.

It’s true that everything about cancer is complicated. If it were straightforward, we would have found a cure by now. Furthermore, when it comes to guidelines to follow, people don’t want details, they want sound bites. But simplification cuts out information. For example, this CDC webpage about what you can do to lower your breast cancer risk posts recommendations geared for older women, including maintaining a “healthy weight”, but the photo that’s shown is clearly of two younger women.

Even a cursory glance at the research reveals what a difference menopausal status makes. In addition to extra weight seeming to have a protective effect in premenopausal women (Cold et al., 1998, Eur J Cancer; Lahmann et al., 2004, Int J Cancer), it’s also been determined that greater red meat consumption in adolescence is significantly associated with increased risk of breast cancer in premenopausal women (Farvid et al., 2015, Int J Cancer). Interestingly, higher quality diets have a more beneficial effect on the risk of postmenopausal women and seemingly no effect on premenopausal ones (Haridass et al., 2018, J Nutr). I would expect that a more exhaustive search would yield even greater differences.

So what does this tell us? This is less about the specific differences between pre- and postmenopausal breast cancer risk, and more that there simply is a difference. At this point in our knowledge, we are still putting together pieces of the cancer puzzle.

Additionally, many studies that offer preventative guidelines are based on other studies–they may be meta-analyses of previously collected data from a broad range of subjects. The data may be self-reported, which may result in recall error. And when you have a sample size of ~30,000 women, you’re talking about general risks for populations, not a specific risk for a specific, and very unique, individual: you.

All this sounds exasperating, but one concept holds true: no matter what your risks, the healthier you are before you’re diagnosed with cancer, the better your outcome compared to someone with less healthful habits, should you get the disease. Instead of obsessing about possible risk factors, give yourself the respect you deserve–put the effort into improving lifestyle habits to grant yourself the best chance for survival. In the end, that’s what matters.