The rub: Only 20 percent of ovarian cancers are discovered at an early stage, according to the American Cancer Society, because ovarian tumors are very difficult to detect. One of the main problems making early detection of ovarian cancer so difficult is that we don’t have efficient screening tools for it, as we do for breast cancer, and its signs and symptoms are usually vague and nonspecific, says Marilyn Huang, MD, the director of translational gynecologic oncology research at the University of Miami Miller School of Medicine in Florida. Some of these signs — such as abdominal bloating, indigestion, nausea, and changes in bowel movements — overlap with and are often confused with the symptoms of a very common gastrointestinal problem: irritable bowel syndrome (IBS). RELATED: Home Remedies for Gas and Bloating

What Are the Symptoms of IBS vs. Ovarian Cancer?

If you compare the symptoms of IBS and ovarian cancer, you’ll see why ovarian cancer sometimes gets mistaken for IBS in the beginning stages. The symptoms of ovarian cancer include:

Abdominal bloatingIndigestionNauseaPressure in your pelvis and backDecrease in appetite or feeling full soon after eatingUnexplained weight lossChanges in bowel movementsMore frequent urination or urgency

Meanwhile, the symptoms of IBS include:

Abdominal pain (often accompanying bowel movements)Changes in bowel movementsBloatingFeeling of having incomplete bowel movementsWhitish mucus in your stool

RELATED: 10 Ways to Get Rid of Bloating

IBS and Ovarian Cancer: Sorting Out Symptoms

Why are the symptoms so similar? “The ovaries are attached to the uterus and dangle off the uterus, meaning they’re free-floating in the pelvis,” explains Dr. Huang. The small bowel also free-floats in the abdominal pelvic cavity. As an ovarian mass grows, it can become attached to the intestines and affect how they function, she explains. Because of that, the initial symptom — one often ignored by women and even the initial providers they see — is a vague sense of pressure or discomfort in the abdomen, along with crampiness. Another defining symptom of ovarian cancer that the two disorders share is bloating. In the case of ovarian cancer, it occurs as a result of fluid collecting in the belly. In the case of IBS, bloating may be triggered by what people consume, such as fiber-rich foods, fried fatty foods, and carbonated drinks. With the overlap in symptoms, it can be hard to tell what’s causing them. But one clue may be whether the symptoms come and go or get progressively worse. “Irritable bowel syndrome is a chronic problem, and its symptoms are intermittent,” says Adnan R. Munkarah, MD, the executive vice president and chief clinical officer of the Henry Ford Health System in Detroit. “Cancer is a disease where symptoms continue to progress.” If you’re concerned about symptoms, your best bet is to talk to your gynecologist and ask if testing is necessary. RELATED: Dead Probiotic Bacteria May Help IBS Sufferers Find Relief

Testing for Ovarian Cancer

Vague abdominal symptoms should raise suspicion, especially if you are a woman in her midfifties to early sixties, when the disease is most commonly diagnosed. In this case, your gynecologist should be your first stop. “Ovarian cancer [should] be considered as a possible diagnosis when a woman has these symptoms,” says Dr. Munkarah. “Proper radiologic imaging needs to be performed to rule out ovarian cancer before a woman is given the diagnosis of irritable bowel syndrome,” The most common tools used to begin to evaluate whether ovarian cancer is present are an ultrasound and a blood test known as CA-125, which tests for proteins associated with ovarian cancer. If those tests are negative, your doctor will discuss next steps — including whether your next step is to be evaluated for IBS.