Despite decades of cancer treatment progress, black and white survival rates remain different: CDC

— -- Despite years of improvements in cancer care, the disease still disproportionately kills black people, according to three sobering new reports from a study funded by U.S. Centers for Disease Control and Prevention.

The CDC's findings on ovarian, breast and colon cancer survival, published in the journal Cancer, come at a time when reports show that that overall cancer death rates have declined every year since 1999 in the U.S.

It is important for people, no matter their race, to be proactive in their own healthcare, Dr. Sherri Stewart of the CDC, who is also an author of one of the reports, said in a statement issued to ABC News. This means looking up routine cancer screening schedules, getting educated on warning signs and symptoms, and advocating for access to primary care.

"Symptoms that signal the presence of the disease are almost always present," she said about ovarian cancer. "If those symptoms are recognized early, women have a better chance of a stage I or II diagnosis, leading to earlier treatment and better survival."

Using large amounts of data from 80 percent of the U.S., some of the largest studies ever done in the U.S. on cancer survival in specific populations, researchers compared the number of black patients who survived at least five years after a cancer diagnosis to the number of white patients who survived in the same period. They found that at least 10 percent fewer black patients lived past five years after being diagnosed with breast, colon or ovarian cancer compared to white patients.

According to the CDC, these three cancers are among the top 10 causes of cancer deaths in the U.S.; breast cancer is the second-leading cause of cancer deaths among women and colon cancer is the third-leading cause of cancer deaths in both men and women.

Even at the one-year mark after diagnosis, researchers reported that blacks and whites experienced unequal rates of survival.

In fact, this finding held true over the entire nine years of the study, at each period measured past survival: one, three and five years.

One concerning situation found in the research was that more black people were diagnosed at later stages of the three cancers studied –- and people diagnosed with more advanced-stage cancers usually have worse outcomes. But, even with earlier stages of cancer diagnoses, fewer black people survived five years out.

The researchers did not measure specific causes for the disparity. However, they hypothesized that differences in cancer screening between these groups may play a part.

Dr. Jacqueline Miller, one of the authors of the report on breast cancer survival rates, is a general surgeon who has now been with the CDC for more than a decade. She was inspired to do this work because she saw many women from underserved populations in her practice who didn't have health insurance and therefore did not have good access to care.

"Even though we know about disparities, there’s still a huge gap that needs to be narrowed. They need care that is equal," Miller said. "They need to be diagnosed timely, get treatment timely and complete treatment."

Researchers added that the difference in diagnosing advanced ovarian cancer, for which there is no standard screening, may mean that there are systemic differences in access to doctors or medical treatment for black women. Earlier detection and treatment of ovarian cancer makes a big difference.

"Many women mistakenly believe that the Pap test can detect ovarian cancer, but it does not," Stewart said. "Recognizing early symptoms of ovarian cancer and seeking timely care may help lead to detection of the cancer at an earlier stage, where treatment is likely to be more effective. Symptoms, such as abdominal and back pain, feeling full quickly after eating, and frequent urination, are often present."

She said education specifically for black women about the symptoms may help with earlier detection and, in turn, better survival rates.

Other possible factors in why black patients tended to have worse overall rates of cancer survival could include racial differences in treatment follow-up, disease management, health beliefs –- and perhaps the biology of some cancers.

"We know that there are biological differences in tumors, socioeconomic status which affects access to care, but there’s a huge gap," Miller said. "The key is getting the right treatment to the right woman at the right time."