A radiologist checks mammograms for signs of breast cancer in Los Angeles. Damian Dovarganes/AP
As the second leading cause of death in the United States, behind heart disease, cancer remains a formidable public-health problem, accounting for 1 in every 4 Americans’ deaths. But after peaking in the 1990s, cancer death rates have plummeted by 20 percent in the last two decades, largely because fewer Americans are smoking, according to a new report from the American Cancer Society (ACS).
The report, an annual forecast of the number of new cancer cases and how many people are expected to die of it in the coming year, said that of particular note were figures that suggest black men saw the most dramatic declines in cancer death rates in the last 20 years, with a 55 percent decrease among those ages 40 to 49 and with significant drops in every other age group.
Black men have historically fared the worst among all demographic groups in terms of cancer deaths; they die of cancer at about twice the rate of Asian-Americans, for example. But because many black people picked up the habit of smoking cigarettes and other tobacco products at much lower rates than white people did, starting in the late 1970s, they have a much lower prevalence of lung cancer today, according to Rebecca Siegel, an epidemiologist at the American Cancer Society and a co-author of the report.
Even so, black Americans still have higher cancer death rates than white Americans do, and that’s likely because of socioeconomic differences, the report suggests.
“Cancer death rates are associated with access to care,” Siegel said. “Individuals who have lower socioeconomic status have much higher death rates than more affluent individuals,” who are more likely to have health insurance, engage in exercise and have better access healthy foods like fruits and vegetables — all of which decrease cancer mortality rates.
In particular, people who don’t have health insurance or who are on Medicaid are more likely to be diagnosed with advanced cancer, which is much harder to treat than cancer that is detected early. Census data have shown that 20 percent of black Americans are uninsured, compared with 11 percent of whites.
Vanessa Sheppard, an oncology professor and assistant director for health disparities research at the Georgetown Lombardi Comprehensive Cancer Center, said race-based differences in cancer death rates are caused by a complex mix of behavior, biology and access to health care. “Race is a marker of the experience that one brings,” she said.
For example, black women are less likely to survive breast cancer than white women, a problem that was brought about by a lack of access to health care after advances in detection. “There was a time in the U.S. where we really didn’t have some of the racial disparities that we see now,” she told Al Jazeera. Before there were screening techniques like mammography, black and white women died of breast cancer at similar rates, she said.
Sheppard said black Americans have also experienced higher cancer death rates because of an increased likelihood of hypertension, heart disease, diabetes and other obesity-related diseases. “We need attention to diet and exercise,” she said. “It is something that’s low cost. You don’t have to get a prescription for it. We need intervention at the policy level and also at the individual level to empower people to make healthy choices for their diets.”
Both scientists hope the Affordable Care Act, President Barack Obama’s landmark health care legislation, will make a big difference.
“Of course, it will take time to see the effects,” Siegel said. “In theory, if most people who don’t have insurance now are able to get health insurance and access to good-quality care, then these disparities we should see shrinking in the next 10 to 20 years. So it’s very exciting for us.”
This year’s ACS report, which was compiled with statistics from the National Cancer Institute, the Centers for Disease Control and Prevention and others, projects that there will be a total of 1,665,540 new cases of cancer and 585,720 cancer deaths in 2014.
Cancer death rates started rising in the 1970s and peaked in 1991, at about 215 deaths per 100,000 people, and plummeted to 171.8 deaths per 100,000 people in 2010. The strong decline “translates to the avoidance of approximately 1,340,000 cancer deaths,” the report said, totaling some 952,700 men and 387,700 women.
These declining numbers, researchers say, reflect improvements not only in cancer treatments and cancer prevention but also in Americans’ smoking rates, which began gradually waning in the mid-1960s, as urged by the 1964 report from then–Surgeon General Luther Terry, which first warned Americans that smoking was hazardous to their health.
Overall, woman are found to have 23 percent fewer incidents of cancer than men, the ACS report said, although cancer death rates decreased among men by about 1.8 percent from 2006 to 2010, versus by 1.4 percent in women during the same time frame. Men have a 43.9 percent chance of getting cancer in their lifetime, while women have a 38 percent chance.
Researchers don’t know why women have significantly lower cancer incidence than men do, but they suspect it’s also due to smoking habits.
“It's probably due to more men who are smokers than were women, historically,” Siegel said. “And of course, we don't see the effects of that risk factor for 30 or 40 years, which is why we are just now seeing these large decline in death rates.
A factor that could explain different rates between the sexes is that men may have been more likely to work in conditions associated with a higher cancer risk, like exposure to chemicals. Or the imbalance could be attributable to hormonal differences.
As for different types of cancer, prostate cancer among men and breast cancer among women are the most common types, at 27 percent and 29 percent of all new cases, respectively. The second most frequent is lung and bronchus cancer, which accounts for 14 percent of all new cases for men and 13 percent of all new cases for women.
The high rates of these types of cancers have as much to do with their frequency as with increased detection and awareness, Siegel said. Often these cancers are diagnosed early, when they’re still localized, so “incidence rates are fairly flat while death rates are declining,” she said.
The fastest growing types of cancer in the U.S. are thyroid and melanoma. The former, Siegel says, could be attributed to improvements in awareness and diagnosis, and death rates are very low because of early detection.
In terms of melanoma, death rates are also low, and detection has improved. The pattern is a bit like smoking: Awareness about how too much sun exposure can damage skin eventually led to more sunscreen use, but the lack of sun protection during many baby boomers’ childhoods is leading to skin cancer today. "But it is a concern that melanoma rates are increasing," she said.