When it comes to determining whether or not to have a screening test for prostate cancer -- or any cancer for that matter -- patients are told to weigh the benefits against the risks. But public health experts point out that putting a few extra years of life on one side of the balance and debilitating treatment side effects on the other is like comparing apples with oranges.
What patients really need is an equation that will consider their age, health status, and personal fears about dying or having a reduced quality of life in order to determine whether they will have a net gain or net loss from a particular screening test. That’s exactly what Dutch researchers did for PSA screening in a new study published in the New England Journal of Medicine.
The researchers took data from a European trial which found that men who were screened yearly for the prostate specific antigen or PSA from ages 55 to 69 had nearly a 30 percent reduced risk of dying from prostate cancer but that they also “lost” a certain number of quality years due to getting diagnosed and treated for cancer earlier in life and experiencing sometimes permanent side effects like urinary incontinence and sexual dysfunction.
Overall, the study found that men, on average, gained a small amount in their lifespan from screening which was measured in “quality-adjusted life years.” For every 1000 men regularly screened with PSA, the total number of these quality-adjusted life years gained was 56. (That would mean each man would gain .56 of a year or nearly seven months on average from PSA screening.)
In other words, the government task force that recommended against PSA screening three months ago may have been too hasty in concluding that screening brings more harms than benefits.
“Individuals and their physicians should discuss and decide for themselves,” study leader Evenline Heijinsdijk told me via email. “We think that limited screening can be useful; therefore we do not fully agree” with the task force.
No question, however, some men may have a net minus from regular PSA screening. The researchers calculated that the number of quality life years that resulted from PSA screening ranged from a loss of 21 years to a gain of 97 years depending on men’s attitudes about side effects, getting diagnosed with cancer earlier, and living as long as possible even if that means wearing a diaper or not having sex.
“To calculate this, researchers have to ask each man how many years of life they’d be willing to give up to live without incontinence,” said Dr. Harold Sox, from the Dartmouth Institute of Health Policy and Clinical Practice who wrote an editorial that accompanied the study. “One man might say he’d be willing to give up one year, while another may be willing to give up five years.”
That type of reasoning called “time trade-off” has been used in a variety of medical scenarios to help patients make informed decisions. For example, an 80-year-old woman who’s diagnosed with breast cancer might be asked whether she was willing to give up two years of her life to avoid going through chemotherapy and a mastectomy.
Sox said he doesn’t agree with the new recommendation against screening but thinks men should consider PSA testing as part of an informed decision making process with their doctors. “Before I saw this new study, I thought the task force made a reasonable recommendation given the frequency and severity of side effects from prostate cancer treatments,” he explained. “But the evidence suggests that men can either gain or lose.”
Back in the 1990’s, Sox , himself, served as head of the expert group called the US Preventive Services Task Force. “I’ve now come to the conclusion that task force should reconsider its recommendation.” He thinks men ages 50 to 70 should get the same advice about PSA screening that women in their 40’s get for mammograms: the decision on whether or not to screen should be an individual one that patients make with their doctors.
(The task force recommends mammograms for women aged 50 to 74, and most experts agree that men over 70 shouldn’t get PSA screening.)
Dr. Anthony D’Amico, chief of genitourinary radiation oncology at Brigham and Women’s Hospital, agreed. “Most men will get positive gains from PSA screening but to make everyone a winner, doctors have to do more education.” He’d like to see a discussion not only about PSA screening itself but the specific steps that may follow an elevated reading such as a biopsy and the possible diagnosis of slow-growing cancers that might not need to be immediately treated.