It's long been observed that African-Americans diagnosed with cancer seem more likely to die from the disease than patients of other races. Many social scientists and public-health experts have assumed that the poor prognosis for blacks results from socioeconomic factors that prevent them from getting the best possible medical care in a timely fashion.
But a groundbreaking study suggests the survival gap for at least some types of cancer may also be rooted in biology. In other words, blacks may inherit certain genetic traits that make their cancers especially lethal.
The study looked at what happened to more than 19,000 patients enrolled in 35 clinical trials conducted in the United States and Canada. The patients included people from all racial backgrounds, including blacks, Caucasians and Asians. Essentially that means the researchers were reviewing the medical outcomes of people who received equivalent treatment, regardless of race.
“It was a level playing field for everyone,” said lead researcher Kathy Albain of Loyola University Medical Center in Maywood, Ill. “Patients of all races had the same doctors and received the same state-of-the-art treatment.”
The study, published in the Journal of the National Cancer Institute, revealed that even when blacks received the same care as all other patients, their survival rates were still lower for breast, ovarian and prostate cancers. (There was no significant racial difference in survival rates for other types of cancer such as lung and colon cancers, leukemia, lymphoma and myeloma.)
“Our study casts doubt on the prevailing theory that African-Americans have lower cancer survival rates because of poverty, poor access to quality care or other socioeconomic factors,” at least when it comes to breast, ovarian and prostate cancers, she said in a statement released along with the research paper.
According to the study findings, blacks were:
61 per cent more likely than people of other races to die from advanced-stage ovarian cancer;
49 per cent more likely to die from early stage postmenopausal breast cancer;
41 per cent more likely to die from early stage premenopausal breast cancer;
21 per cent more likely to die from advanced stage prostate cancer.
In a telephone interview, Dr. Albain noted that a wide range of genes could affect a person's chances of beating cancer. For instance, some genes play a role in how the body responds to cancer therapy and, in some cases, can reduce the effectiveness of the treatment.
She said it's possible that blacks are more likely to be born with various gene combinations that minimize their survival odds.
Furthermore, breast, ovarian and prostate cancers are generally linked to gender. So sex hormones may be involved.
Dr. Albain said researchers are planning more studies to explore the interactions between tumour biology, genes, sex and race. That work may eventually lead to new treatment strategies that boost patient survival.
