Uterine cancer is the fourth most common cancer—and the seventh most common cause of death from cancer—among women in the United States. But recent news suggests that the disease is becoming even more prevalent, which has health experts alarmed.
According to a December 2018 report from the U.S. Centers for Disease Control and Prevention (CDC), uterine cancer rates have risen over the last two decades, even as most other forms of cancer have declined. Here’s why doctors suspect that’s the case, as well as other important facts women should know about this disease.
There are two main types of uterine cancer
Uterine cancer is a term for any cancer that starts in the body of the uterus. More than 90% of these cancers occur in the lining of the uterus, called the endometrium, according to the American Cancer Society (ACS). Endometrial cancer is the most common of all gynecological cancers, which also include ovarian, cervical, and vaginal cancer. (Even though the cervix is in the lower end of the uterus, cervical cancer is not considered a uterine cancer.)
Another type of uterine cancer is uterine sarcoma. This type of cancer forms in the muscles and connective tissue of the uterus and is much less common—making up only about 4% of all uterine cancer cases.
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Diagnosis and death rates have increased since 1999
The CDC report, published in December 2018 in Morbidity and Mortality Weekly, found that the rate of new cases of uterine cancer increased 0.7% per year between 1999 and 2016, for an overall 12% increase over the study period. The death rate also increased by 1.1% a year, or 21% overall.
In 2015, a total of 53,911 new uterine cancer cases were reported in the U.S., according to the CDC, and 10,733 women died from the disease. That’s about 27 new diagnoses, and five deaths, per 100,000 women.
“In my career, I’ve seen it almost double,” says Beth Karlan, MD, professor of obstetrics and gynecology at UCLA’s David Geffen School of Medicine, who speaks often about the disease. “I have to keep remaking my slides on endometrial cancer, over and over, because the numbers keep going up. It’s really quite concerning, and an area that’s worthy of more research.”
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Black women are disproportionately affected
The report also found that diagnosis rates were higher among white women and black women than among Hispanic, Asian, or Native American women. Uterine cancer deaths were about twice as high among black women—about nine deaths per 100,000 women—compared to all other groups.
One reason for that difference in death rates may have to do with the type and stage of cancer: Black women in the study were more likely to be diagnosed with rarer, more aggressive forms of uterine cancer, and also to be diagnosed later in the disease’s progression.
Obesity may play a role
Scientists know that women who are overweight or obese are about two to four times as likely to develop endometrial cancer than women who maintain a healthy weight. (Fat tissue produces estrogen at unhealthy levels, which can fuel hormone-sensitive cancers.) Therefore, they are pretty confident that the nation’s ballooning obesity problem has something to do with why uterine cancer rates are also on the rise.
In the later years of the study—between 2013 and 2016—about 40% of women in the U.S. (and about 56% of black women) were obese, according to the CDC report. “Clearly obesity is an epidemic, and simply telling people that they need to lose weight is not going to solve the problem overnight,” says Dr. Karlan.
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Access to health care is probably part of it too
Black women and other racial and ethnic minorities are also less likely to have health insurance and adequate access to doctors. That likely explains part of their higher death rate from uterine cancer, says Dr. Karlan—but even when studies take these factors into consideration, health disparities still exist.
“We don’t know exactly why this is, and it’s most likely a number of different things—both genetic and environmental,” says Dr. Karlan. “We hear a lot these days about the microbiome, and about dietary issues, and there’s a lot we still don’t know.”
Uterine cancer is usually diagnosed early
If there’s good news about uterine cancer, it's that it usually causes symptoms that can help doctors diagnose it early. Specifically, it can cause abnormal bleeding—between periods, after sex, or after menopause. It can also cause non-bloody abnormal discharge, weight loss, and pelvic pain, according to the ACS.
Because uterine cancer tends to be obvious and is usually caught early, there is no recommended screening for women who don’t have symptoms. For women who do have suspicious symptoms, doctors will generally perform an ultrasound and take a tissue sample, either through a biopsy or a procedure called dilation and curettage (D&C). If cancer is detected, more tests may be needed to see if it has spread to other organs.
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Risk is greatest after age 55
Pre-menopausal women aren’t generally at very high risk for endometrial cancer, which usually occurs in women over 55. “That’s why most women are diagnosed in stage 1—because these women have been through menopause and then they start to have pink discharge or abnormal bleeding,” says Dr. Karlan. “If you haven’t had your period for six months and you start bleeding again, you should see your doctor.”
However, says Dr. Karlan, doctors have seen an uptick in cases among younger women—especially over age 35—in recent years. “If you notice your period is suddenly heavier or more frequent, or you’re bleeding when you shouldn’t be, that should be discussed with your physician,” she says.
Irregular ovulation is a risk factor
In addition to obesity and family history, having irregular periods is also a risk factor for uterine cancer. Skipped periods can result in excess estrogen circulating in the body, which can cause the cells in the uterus to grow out of control.
Women can have irregular periods for a number of reasons, but a major cause is polycystic ovary syndrome (PCOS)—an under-diagnosed condition that’s much more common than once thought, says Dr. Karlan. PCOS can lead to infertility and can also cause acne and abnormal hair growth. “The patients I’m worried about are the ones who say they’ve had trouble getting pregnant, or they’re overweight, or their periods are very irregular,” says Dr. Karlan.
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Using hormonal birth control may be protective
In one of the largest and longest-running studies on this topic, published in 2017 in the American Journal of Obstetrics and Gynecology, researchers found that being on the pill was associated with about a 33% reduced risk of developing endometrial cancer. It was also linked to lower risks of ovarian and colorectal cancer as well.
Prognosis for most women is good
If uterine cancer is diagnosed before it spreads to other parts of the body, women have a very good chance of recovering. According to the CDC, the five-year relative survival estimate is 80 to 90%. Treatment usually involves surgery and may include removal of the uterus, fallopian tubes, and ovaries.
Depending on whether the cancer has spread to other parts of the body, radiation or chemotherapy may be performed as well. Treatment can be more difficult for younger women who still hope to become pregnant, says Dr. Karlan. But for those with early-stage cancer, hormonal therapies can sometimes be used to delay their need for surgery and give them a chance to start a family.
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