Breast Cancers Are Rising in Younger And In Older Women: Reasons For Concern

A new JNCI report by NIH researchers examines breast cancer trends in U.S. population and cancer registry data. The analysis finds that the most common forms of invasive and non-invasive breast tumors, those that are estrogen receptor (ER) positive, have been rising steadily in recent years. The trend applies, with varying degree, to women in all age groups studied: 30 to 39, 40 to 49, 50 to 69, and 70 to 84 years.

Based on observed data – what’s been seen so far – the investigators project the total number of breast cancers will climb by around 50 percent, to approximately 440,000 U.S. cases per year, in 2030. Over 70 percent of the expected breast cancers, or disease burden, will be invasive. Intriguingly, almost all will be hormone receptor positive, confirming a two-decade shift in subtype trends.

The work comes from the Biostatistics Branch in the Division of Cancer Epidemiology and Genetics at the National Cancer Institute (NCI). Philip S. Rosenberg PhD., the lead author and a senior NCI investigator, presented some of these results at the recent AACR meeting in Philadelphia. He and colleagues used mathematical models to explore NCI Surveillance, Epidemiology, and End Results (SEER 13) data for different subtypes of breast cancer.

And while I wouldn’t panic, this is a big deal. This report has implications for breast cancer screening, particularly for women under ages 40 to 49 years, about which recommendations are now in flux, and for how to best manage so many invasive, ER positive (ER+) forms of breast cancer, which are highly treatable in most cases and especially those found early, and of non-invasive tumors, like DCIS (which may not need much if any treatment), in younger and in older women.

One aspect of the analysis that caught my attention during the AACR presentation, and is borne out by the now-published supplemental data, is that invasive ER+ breast cancer cases have been rising, steadily, in all four age brackets analyzed, including pre-menopausal women. Among those 30 to 39 years, the rate of invasive ER+ breast cancer climbed by 1.6 percent per year, on average, between 1992 and 2010; this translates to a rise of 17 percent over a decade. Among women 40 to 49 years, the rate of invasive, ER+ breast cancer increased by 1.9 percent per year, on average, between 2002 and 2010.

These findings support that the rate of the most common (and treatable) forms of breast cancer, ER+ invasive cancer, is currently rising at a rate of 21 percent per decade in U.S. women ages 40 to 49 years. Worrisome, especially if we pull back on screening.

The hike in invasive cases cannot simply be explained by screening. Here’s why: the CDC’s NCHS data on mammography use (Fig. 13) reveal that screening’s been flat since 2000. Among U.S. women under 50 years, mammography use declined during the timeframe that reported cases climbed. (One caveat, not considered in the NCI paper, worth considering, is this: if mammography has improved since 2000, and there’s every reason to think that it has, detection would be more efficient, and so there’d be more invasive cases, as has been documented, despite the trend away from screening.)

The study authors emphasized that breast cancers in women between 70 and 84 years will go up disproportionately, from just 24 percent to over a third (35 percent) of all breast cancers. This, in itself, is a significant observation. The oncology community knows comparatively little about optimal management of women in that age group, who are, in general, at greater risk of dying from other causes, heart disease and other problems. It could be, for instance, that for a women over 75 years with a small invasive ER+ tumor that is unlikely to recur, as assessed by OncotypeDx or MammaPrint or another pathology test, the best treatment is simply to remove cancer by lumpectomy with clear margins. Depending on the woman’s age, overall health and preferences, she might want to skip radiation and take a hormone-blocking drug, or just do nothing more. It could be, for older women who have non-invasive malignancies, like DCIS or LCIS (which some people say shouldn’t be called “cancer”), that observation is best.

All of this – what’s best for managing breast cancer in women over the age of 70 years – is unknown. With the projected burden of cases to affect this demographic so heavily, prospective clinical trials are warranted, starting ASAP. If less treatment, such as observation after lumpectomy for small invasive tumors, and observation for DCIS, proves best, then we’d be saving a lot of health care expenses, and toxicity, if we could learn these answers before 2030.

As for the increasing invasive, ER+ breast cancers in younger women, those can’t be ignored. Breast cancer is the leading malignant killer of women under age 60 in the U.S., and is one of the most common causes of death in women between the ages of 35 and 60 years, worldwide. Not treating invasive breast cancer in healthy people who are otherwise expected to live for decades would be unethical.

Finally, it’s worth mentioning that this study is a small fraction of new, SEER-related work ongoing at the NCI. The agency, as documented in the first-ever report on breast cancer subtypes in this year’s annual Report to the Nation, is looking at pathology details beyond the traditional incidence and death rates. They biostatistics group is looking at recurrences, treatment, hormone receptor status, Her2, and more details, including molecular pathology.

I look forward to reading more reports like this, based on analyses of population data, so we can understand trends in the disease, what’s causing some forms to rise and others to drop. That information might offer clues about breast cancer’s causes, optimal treatment including less therapy for some types, and prevention.