Cancer remains a major health obstacle across the globe, but now it looks like rare forms of cancer are becoming more common.

According to a study published in CA: A Cancer Journal for Clinicians, 1 in 5 cancers diagnosed in America is considered a rare cancer. Rare cancers are those with less than six cases per year per 100,000 Americans.

Carol E. DeSantis, MPH, the director of breast and gynecological cancer surveillance for the American Cancer Society, conducted the research using data from the North American Association of Central Cancer Registries, and the Surveillance, Epidemiology, and End Results (SEER) program. She looked at more than 100 types of rare cancers.

Rare cancer rates were higher in Hispanics, Asians, and Pacific Islanders compared with non-Hispanic blacks and non-Hispanic whites. Also, 71 percent of cancers in children and adolescents were rare, while less than 20 percent of cancers in Americans 65 years of age and up were rare.

Does this mean that rare cancers are on the rise? Not quite, according to Dr. Maurie Markman, president of medicine and science at Cancer Treatment Centers of America.

Now that we can see cancers at the molecular level, we are able to better identify them — and that’s why you see rarer cancers being diagnosed.

“The diagnosis of cancer is still a histological one,” Markman told Healthline. Doctors can better pinpoint different types of cancer and subsets due to all the breakthroughs. This is why doctors can better predict how patients will respond to different treatments.

“Cancers are increasingly being subdivided into groups of cancers based on molecular profiling. The more precise definition of cancers will result in more people being diagnosed with a rare cancer,” DeSantis told Healthline.

DeSantis explained that rare cancers are inherently more difficult to study as there are fewer patients and less research money to fund these studies. However, progress is being made to overcome some of these challenges through collaboration and novel study designs.

“I think the proliferation of rare cancers is actually an indication that we are getting ahead of cancer, as it reflects our increasing knowledge and understanding of cancer,” DeSantis added. “The more precisely we can define a cancer, the better we will be able to target and treat that cancer.”

Targeted treatments bring hope

While there may not be as much research done on rare cancers as types that are more widely known, new drugs are hitting the market to target rare cancers — something that Markman finds encouraging. When a rare cancer drug gets approval from the Food and Drug Administration (FDA), insurers are more likely to cover it, which is a boon for people with these uncommon diseases.

“The increase in the proportion of rare cancers calls for more funds in research in these diseases, which may not have benefitted from advances as much as more common cancers,” Dr. Paolo Boffetta, MPH, the associate director for cancer prevention at the Tisch Cancer Institute at Mount Sinai in New York, told Healthline.

Rare, but still risky

When talking about rare cancers, it’s important to remember that the type of cancer may not be common, but the impact of the cancer can be just as devastating to the patient and their family, Markman said.

Being able to target rare cancers more affordably and create treatments based on those advanced detection methods may mean that more people with rare cancers will receive treatments as effective as treatments used to battle more common types of the disease.

DeSantis noted that a cancer diagnosis is always a challenge — regardless of the type.

“But diagnosis with a rare cancer presents additional challenges which may include difficulties and delays in diagnosis, more limited treatment options, and a general lack of information and support,” she noted.

Recent breakthroughs include a trial that improved three-year survival rates for 23 percent of bile duct cancer patients who took the medicine capecitabine after surgery. Another study used immunotherapy to treat malignant pleural mesothelioma (MPM), which is a rare cancer linked to asbestos exposure.

These are the types of developments that give Markman hope for treating rare cancers.

“For those tumors and those patients and those patients’ families, this is an incredible ray of hope,” Markman said. “It’s potentially revolutionary in how we begin to view cancer.”