Most types of cancer are decreasing nationwide, but uterine cancer is proving to be a stubborn exception, and it’s taking its greatest toll on African-American women, federal researchers said Thursday.

This rise is due in part to the epidemic of overweight and obesity in the U.S., the Centers for Disease Control and Prevention said in a weekly report.

“There are many risk factors for developing uterine cancer," said Dr. Joseph Davis, an OB-GYN and medical director of the Cayman Fertility Center in the Caribbean who was not involved in the report. The lining of the uterus is hormonally sensitive, so people with higher-than-normal estrogen are especially at risk, "but there are also social factors that contribute to this increase," he told NBC News, "like diabetes and obesity that have become more and more common with the introduction of processed foods in our diet.”

Uterine cancer is the fourth most common cancer and the seventh most common cause of cancer death among U.S. women. Over 53,000 new cases were diagnosed in 2015, the CDC says.

The researchers found that the rate of new cases of uterine cancer increased 0.7 percent per year from 1999 to 2015, and that death rates increased 1.1 percent per year from 1999 to 2016, with smaller increases observed among non-Hispanic white women than among women in other racial or ethnic groups. While new cases of uterine cancer were higher among both black and white women than among other racial/ethnic groups, deaths from the disease were twice as high for black women.

Dr. Michael Birrer, an oncologist and director of the O’Neal Comprehensive Cancer Center at the University of Alabama at Birmingham, said he was not surprised by the report.

“There’s no doubt that the incidence and mortality of uterine cancer, specifically endometrial cancer, is higher in African-American women," he said. "The reason why is not entirely understood. One reason could be genetics. Another is access to health care. Black patient populations that are poor or from rural communities may not have equal access to care. When the tumors are finally identified, the disease may have already spread."

The most common type of uterine cancer is endometrial cancer, which occurs most often in women over 55. The cancer strikes the endometrium, the lining of the uterus, when too much estrogen is produced. Women who do not ovulate regularly, such as those with polycystic ovary syndrome or those on hormone replacement therapy, are at greater risk. Using birth control pills is generally seen as protective because the pills contain progesterone, which counters the effects of estrogen and inhibits the growth of abnormal endometrial cells.

"Obese women have higher circulating levels of estrogen, so that tends to put them at higher risk,” said Birrer.

Endometrial cancer is often detected at an early stage because it frequently produces abnormal vaginal bleeding, which prompts women to see their doctors. If endometrial cancer is discovered early, a hysterectomy is often a cure.

Other common symptoms include pelvic pain, bleeding between periods, and bleeding after menopause.

The CDC called for public health efforts to help women achieve and maintain a healthy weight and adopt sufficient physical activity to reduce the risk of uterine cancer.

“Public health awareness is important, but more research needs to be done to address all the genetic and environmental factors that contribute to the difference in prevalence between African-American women and other groups,” said Birrer.