Blood Tests May Reveal When Cancer Treatments Become Ineffective

By: Dayton Humbles
Monday, March 2, 2015

Some medications, particularly glucocorticoids, are effective at fighting prostate cancer initially but appear to become ineffective or eventually even help the cancer continue to mutate and develop.

However, a study from The Institute of Cancer Research, in London; The Royal Marsden NHS Foundation Trust; and the University of Trento, Italy, suggests that blood tests may be able to detect when treatments are counterproductive.

The late 2014 study demonstrated that tumor DNA circulating in the blood could be analyzed and measured to show how the cancer is responding to medication. This could potentially replace repeated needle biopsies currently used to monitor the tumor, providing a cheaper and less invasive alternative. Researchers hope the blood tests — or “liquid biopsies” — eventually will allow physicians to adjust treatments that could otherwise make prostate cancer more aggressive.

Canadian Medical Officials Weigh In on PSA Screening

Adding a new perspective to a simmering debate, the Canadian Task Force on Preventive Health Care says the prostate-specific antigen (PSA) test should not be used to screen for prostate cancer.

Clipboard Icon 250Between 11.3 percent and 19.8 percent of men diagnosed with prostate cancer through use of the PSA test receive a false positive, and overdiagnosis occurs among 40–56 percent of patients diagnosed via PSA, resulting in invasive treatment, according to the Task Force. Those treatments can lead to infection, incontinence and erectile dysfunction.

The Task Force recommends that even men at high risk not undergo PSA testing. However, its members urge patients and physicians to make decisions jointly about treatment options, even with the PSA test, because different screening methods may be better for different individuals.

The recommendation is in line with that of the U.S. Preventive Services Task Force, though organizations such as the American Cancer Society have been open to broader use of the test.

Prostate Cancer Medications Linked to Deaths from Heart-related Causes

Certain medications for prostate cancer are linked to increased mortality rates from heart-related causes, according to an October 2014 study in BJU International.

Hearbeat Icon 250Androgen deprivation therapy (ADT), a common treatment to reduce male hormones and block their cancer cell-stimulating effect, has previously been associated with conditions including sudden cardiac death and heart disease.

The study did not find a higher risk of heart-related deaths among patients who had undergone ADT but had no prior cardiac issues. However, men who had congestive heart failure or previous heart attacks were at more than three times the risk of cardiac-related death. Given the effectiveness of ADT, the authors recommended its continued use by patients without heart problems. For those with serious cardiac issues, ADT is still an option, but the risks should be carefully weighed.