Thursday, 16 October 2014

Why are black men negatively affected by prostate cancer more than white men?

September 24, 2013

When the US Preventive Services Taskforce (USPSTF) made their startling recommendation against screening for prostate cancer last year there was a widespread outcry from prostate cancer doctors and patients. Resistance was especially strong among black prostate cancer survivors and the doctors who care for them, arguing that the scientific studies that led to the USPSTF recommendation did not include many black men. Is this simply another case of "political correctness?" Isn't prostate cancer colorblind? Doesn't cancer behave the same in all men, regardless of race?  
In reality there are a number of differences in how prostate cancer impacts black men compared to men of other racial and ethnic backgrounds. Black men are 60% more likely than white men to be diagnosed with prostate cancer during their lifetime, and are more than twice as likely to die from the disease. Black men are also diagnosed at a younger age (about 3 years younger on average) and are more likely to have "high grade" tumors - the kind of tumors that grow rapidly, spread to other parts of the body, and often cause death. Research has given us some insights on why these differences exist and what they mean for black men who face decisions about prostate cancer screening and treatment.
Genetic factors may be part of the explanation
A number of genes have been identified in black men that are associated with an increased risk of prostate cancer and with high grade tumors. However, none of these gene differences is found in the majority of black prostate cancer patients, so their role remains a mystery.
Socio-economic factors make a huge difference
Differences in prostate cancer diagnosis and treatment account for a significant portion of the gap in death rates between blacks and whites, and both are heavily impacted by health insurance.  Black men are less likely than whites to have insurance. Uninsured men have lower rates of screening for prostate cancer, are less likely to see a health care professional quickly for further tests if they have abnormal screening results, and are more likely to be diagnosed with advanced disease (cancer that has spread outside of the prostate gland, is more difficult to treat and more likely to cause death). Studies of blacks and whites in the military, where men have equal access to health care services, have shown that this equal access gets rid of most (but not all) of the death rate gap.
Education level also may contribute to the excess burden of prostate cancer in black men. "Shared decision making" is an approach used to help patients understand the various options available for their care and to assist them in making decisions that are right for them. This is particularly important in prostate cancer, where men often can choose between several types of effective treatment.
Studies have shown that shared decision making is much less likely to take place when patients have low levels of education, and black men on average have lower educational levels than white men. There is evidence that they don't receive all the information to begin with, or they may not understand it in the way it's presented. That means they may not be fully aware of the possible consequences of treatment and end up regretting their choice.
'Race-specific' evidence missing
Even when information is shared, it may not be complete or accurate information - at least as it relates to black men. The overwhelming majority of published prostate cancer research studies include few (if any) black men as subjects.  This means that decisions on prostate cancer screening, diagnosis, and treatment in black men is based largely on what is known about how the disease behaves in white men. 
A study published earlier this summer shows why this is a problem. It looked at the criteria used to identify men with "very low risk" prostate cancer.  Such men may not need immediate treatment for their cancer, but instead can have their disease monitored (an approach called "active surveillance"). 
This study looked at a group of black and white men, all of whom decided to have immediate surgery instead of active surveillance despite having what appeared to be very low risk disease. Surgical findings and tumor analysis after surgery showed that the traditional criteria for determining very low risk disease worked well for white men, but a significant number of black men actually had more risky types of prostate cancer than originally suspected.  If these men had chosen active surveillance instead of surgery they would have experienced higher rates of complications and death from prostate cancer than the white men in this study.
Prostate cancer screening recommendations provide another example of this phenomenon. The major studies used to make those recommendations included more than 250,000 men, less than 5,000 of whom were black. These small numbers mean that the study results can't accurately measure the impact of screening in black men.  Yet, since these are the only large studies available, they have been used to establish screening recommendations for everyone. 
Getting rid of these disparities in prostate cancer will require changes to how we have historically done research.  We must increase our efforts to get more black men included in prostate cancer research, and more emphasis placed on studies geared toward identifying the reasons for and solutions to the excess suffering and death from prostate cancer seen among black men.
What black men currently can do
So what can black men and their health care professionals do right now?  The advice is the same for black men as for all other men: they must learn all that they can about the benefits, limitations, and uncertainties surrounding screening and treatment for prostate cancer.  Because of their higher risk and the fact that the disease hits black men earlier, the American  Cancer Society and other organizations recommend that a discussion about prostate cancer screening begin at age 45 for black men (and at age 50 for men at average risk). Screening and treatment discussions with black men should include their higher risk of developing prostate cancer and dying from it than other men in the US, and acknowledge the things we don't know related to screening and treatment.  Men should then weigh this information in light of their own values and preferences, and make a decision about screening or treatment that is right for them. 

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