The enormous difference in the rates at which whites and blacks die of cancer could be substantially reduced if black cancer patients sought treatment at an earlier stage of their disease, according to a new study of researchers at the Howard Univertity Cancer Center.

The study also adds evidence to the theory that much of the difference in black and white cancer death rates has to do with poverty and the environmental factors associated with the urbanization of rural blacks.

While it has long been known that blacks develop and die from cancer at higher rates than whites, the Howard group, led by cancer center director Dr. Jack E. White and epidemiologist John Enterline, is the first in the country to examine the phenomenon in detail.

The researchers learned last year that blacks in the Washington Metropolitan area die from cancer at a rate greater than their counterparts in the nation's 10 largest metropolitan areas. The new study shows that District of Columbia blacks have a higher cancer death rate than that found in the top 15 urban areas.

According to the new study presented last week in Buffalo, N.Y., at an international symposium on Cancer Among Black Populations, Washington's blacks are 24.7 percent more likely to die of cancer than is the American population at large, while the D.C. area's whites have a cancer death rate .7 percent below the national average.

According to Enterline, "blacks have higher mortality rates than whites, but 70 percent of that difference is attributable to the fact that whites who contract cancer live longer than blacks with similar disease.

"One-half of that 70 percent could be eliminated by early detection," said White, the man credited with launching Howard's cancer program almost 30 years ago. "Survival is worse among blacks at all stages of disease due to their socio-economic status," he said.

White and Enterline, acknowledge that a great deal of the difference between black and white survival may be attributed to the fact that the disease usually is discovered earlier in whites, and is therefore more treatable. But they say that black survival also is hindered by the fact that blacks with cancer are often in poorer health to begin with, and thus less able to withstand the ravages of cancer and cancer treatments.

The new study shows that, when one adjusts for age, whites develop cancer at a rate of 318.9 per 100,000 persons, while blacks develop the disease at a rate of 347.3 per 100,000. This is a difference of 9 percent.

However, the black death rate from cancer is 30 percent higher than the rate for whites, 215.3 deaths per 100,000 persons compared to 165.6 deaths for whites.

According to the Howard researchers, the difference in both the incidence of the disease and death rates in the two racial groups is probably affected by the fact that more blacks live in healthacial groups is probably affected by the fact that more blacks live in heath-threatening urban environments, and tend to work in more menial jobs in industry, jobs that expose them to more environmental cancer hazards.

The study also found that the cancer death rates for rural blacks is the same as the death rate for urban whites. According to Jack White, elimiating the differences in the health care the two groups receive, and the variables imposed by poverty in the black group, conceivably could eliminate the apparent racial differences.