Aggressive uterine cancer rising, particularly for black women

Women aged 30-70 — particularly black women — have been getting aggressive and deadly types of uterine cancer at higher rates in recent years, according to new research published by the National Cancer Institute earlier this week.

Why it matters: Uterine cancer is the most common and second deadliest gynecologic cancer in the U.S. — and in contrast with many other cancers is projected to rise over the next decade. But, certain rarer types of uterine cancer have been rising more rapidly than others, with non-Hispanic black women having the lowest survival rates — and scientists don't know why.

"The underlying causes for the higher proportion of these subtypes, and the survival disparities among non-Hispanic black women, are not well understood. It is likely that a combination of factors, including molecular and genetic, exposure to certain risk factors, and socioeconomic factors are at play."

The backdrop: There are 4 main types of uterine cancer, with endometrial cancer being the most prevalent at roughly 80% of cases.

• Women with endometrioid cancer generally have better prognoses and survival rates, and their disease has been linked to obesity and decreased use of hormone therapy for menopause.
• Meanwhile, the other forms of uterine cancer, such as serous and clear cell carcinomas, are more aggressive, not as strongly linked to hormones, and tend to have worse outcomes and survival rates.

Of note: The study, published Wednesday in the Journal of Clinical Oncology, deliberately excludes women who've had hysterectomies from the population cohort because they cannot get uterine cancer and would skew cancer rates too low, Wentzensen says. "This is particularly important for comparison by race and ethnicity and region."

By the numbers, per the study:

• Women overall had about a 1% increase per year of uterine cancer from 2003 to 2015.
• But, the aggressive, nonendometrioid uterine cancer has been increasing "dramatically" for all racial and ethnic groups from 2000–2015 — at almost 3% per year.
• However, there was significant difference among the races during that period. From 2000–2015, for every 100,000 per racial/ethnic group, these aggressive cancers were found in about 26 black women, 11 white women, 10 Hispanic women and 8 Asian/Pacific Islander women.
• Plus, black women had the lowest survival rates for each stage, suggesting "potential disparities in factors related to medical care," says lead author Megan Clarke.

What's happening: While obesity has been linked to the rise in overall uterine cancers, it's more closely associated with endometrioid cancer, which has been relatively stable over the same period. "Therefore, the obesity epidemic cannot fully explain the observed patterns," Clarke says.

What's next:

"We need to identify risk factors and exposures more specifically associated with nonendometrioid cancers to better understand the strong increases in this subtype among all women, and the particularly high rates and recent increases in non-Hispanic black women. We also need to better understand the factors that contribute to the disparities in uterine cancer survival."

Go deeper:

• Study: Millennials face greater risk of some cancers due to obesity
• Chipping away at the lack of diversity in medical research