News

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.

Injury evades detection

Certain cholesterol-lowering drugs can cause muscle damage in some patients, but the injury can evade detection by doctors, according to a team of U.S. and Swiss researchers.

That's because the blood test normally used to check for muscle injury isn't sensitive enough to pick up all forms of damage, said one of the researchers, Richard Karas of Tufts Medical Center in Boston.

He noted the test measures blood levels of creatine phosphokinase (CPK) – a chemical found inside muscle cells. “The test becomes positive only when there is enough damage that the muscle cells break open and release the chemical into the blood,” he said.

However, patients taking a class of cholesterol-lowering drugs known as statins can have muscle injury without the individual cells rupturing, according to the findings published in current edition of the Canadian Medical Association Journal.

Members of the research team collected biopsies of patients who suffered from severe and prolonged muscle pain. When the tissue samples were examined in the lab, “we found microscopic evidence of damage to those muscles,” Dr. Karas said.

The researchers are not yet sure of the long-term consequences of the muscle damage. And Dr. Karas emphasized that only a small fraction of patients – likely a lot less that 10 per cent – suffer from this type of muscle damage. “It's just those people who have persistent muscle problems lasting for weeks or months … the vast majority are fine.”

He said this select group of patients at risk of muscle damage may want to consider other treatment options for controlling cholesterol – such as different types of drugs or dietary and lifestyle changes.

Statins are among the top-selling drugs on the market today and include brand names such as Lipitor (atorvastatin), Crestor (rosuvastatin) and Zocor (Simvastatin).

A separate study published in the same edition of the CMAJ found that Canadians used more than $5-billion worth of cardiovascular medications in 2006 and statins accounted for almost 40 per cent of this expenditure.

Weighty problems

There seems to be no end in sight to the global obesity epidemic. The U.S. government reported this week that 26.1 per cent of Americans are officially obese, according to the latest measurements taken in 2008. That's up from 25.6 per cent in 2007.

When overweight individuals are taken into account, about two-thirds of Americans are now packing too many pounds.

Canadians have no reason to feel smug. Almost 60 per cent of Canadians have a weight problem, including 23 per cent who are obese, according to figures from several years ago. Overweight is defined as having a BMI – an approximation of body fat based on height and weight – of more than 25, while obesity is indicated by a BMI of more than 30.