By JOHN REICHARD

Survivors of certain types of cancer — melanoma, breast, and prostate — report a quality of life similar to that of adults without the disease, according to a new study funded by the National Cancer Institute.

But survivors of cervical, blood and colorectal cancers have a lower quality of life. Not surprisingly, that’s also the case for malignancies for which the five-year survival rate is below 25 percent, such as liver, lung and pancreatic cancer.

Such differences in quality of life are important to identify, the lead author of the study, Kathryn Weaver, said in an interview Tuesday. That’s because there are things doctors and policy makers can do to improve quality of life among cancer survivors, she said. And addressing the needs of that population is important because its size is growing, the study said. An estimated 12.6 million people in the United States are in that group, and “these figures are expected to continue increasing, largely due to the aging of the population,” said the study, which was published in Cancer Epidemiology, a journal of the American Association for Cancer Research.

The study evaluated the quality of life of 1,822 cancer survivors and compared it to that of 24,804 adults without cancer. It used a 10-item questionnaire to do so. Questions asked respondents to rate physical functioning, depression, pain and fatigue, for example. Data came from the 2010 version of the National Health Interview Survey, conducted annually since 1957 by the Centers for Disease Control and Prevention to take a snapshot of the nation’s health.

Survivors of breast and prostate cancer and melanoma had a health-related quality of life equivalent to or better than adults with no history of cancer, the study found.

But survivors of cervical, blood and colorectal cancer, and of cancers with a five-year survival rate below 25 percent, had a worse quality of life related to their physical health. In addition, survivors of cervical cancer and of cancers with a low five-year survival rate had a worse quality of life relating to their mental health.

All told, 25 percent of the cancer survivors in the study had a lower-than-normal quality of life for physical reasons. Ten percent of them had a lower-than-average quality of life for mental reasons.

That suggests there are 3.3 million cancer survivors in the United States with below-average quality of life for physical reasons and 1.4 million with below-average quality of life for mental health reasons, researchers calculated.

“It is very concerning that there are a substantial number of cancer survivors who experienced poor mental or physical health years after cancer,” said Weaver. She said the results could serve as a baseline to determine in five to 10 years whether approaches for improving the quality of life are working.

Asked whether she was concerned that in a tight budget climate, lawmakers might reduce research and other funding for cancers for which survivors have a relatively good quality of life and redirect funding toward those associated with a poorer prognosis, Weaver said she hopes that’s not the case.

“I would hate for it to be interpreted as a sign we don’t need to continue to focus on these survivors,” Weaver said. The fact that some are reporting relatively good quality of life “could very well be because we have been paying attention to them.”

“Perhaps it’s a sign that we are doing a good job of really addressing the needs of survivors” of cancers such as that of the breast and prostate, she said. Those have been types of cancer that “have been extremely well funded,” she said. “Perhaps this draws attention to some of the other cancer sites where people are not doing as well in the longer term that have not received as much attention.”

Reasons for poorer quality of life beyond the psychological stress of a low survival rate included physical symptoms and treatment side effects. In the case of cervical and colorectal cancer, survival rates were better. But poorer quality of life in the case of cervical cancer could stem from the impact on reproductive health and, in the case of colorectal cancer, from “a lot of difficulty with bowel and bladder function.”

Factors such as fatigue, sleep problems and pain can “last long after the cancer treatment ends,” Weaver noted. But she emphasized that “we do have effective interventions.” They include ways to improve sleep quality and exercise to reduce fatigue “as well as medical interventions. So those, we would hope, would be available to all survivors who need them.”