Concepts in Prostate Cancer Screening – Is a diagnosis as bad as we thought?
By Mark Arredondo, MD FACS
Most men will not develop prostate cancer but we know that increasing age heightens the risk. There’s a one in six chance of being diagnosed with prostate cancer, but only a one in 36 chance of dying from it. A 50-year-old man has a 12 percent likelihood of being diagnosed over the next 30 years to age 80, and 6 out of 10 diagnoses occur in men over the age of 65. Most of these cancers are found by mild elevation of the PSA, which leads to a needle biopsy. The biopsy will most commonly show low risk prostate cancer (called Gleason score, we’ll discuss this below), which we now know is most likely not life-threatening. For example, in a man with a low PSA (less than 10 ng/mL), a low Gleason score, and a cancer localized to the prostate, his likelihood of survival to 5 years from diagnosis is virtually 100 percent and survival to 15 years is about 95 percent. It isn’t that prostate cancer can’t be life-threatening, but it’s only the case in a small minority.
While increasing age has a strong association with prostate cancer, the likelihood is higher for those of African ancestry, men with a family history of prostate cancer, and with a known family history for gene mutation that is associated with breast cancer in women. For average-risk populations, a discussion should begin at age 40 with a strong family history of cancer, 45 if of African ancestry, and otherwise by age 50. For high-risk populations, screening includes PSA blood testing on a yearly basis. The question is whether or not to screen for prostate cancer in the majority of men who are not high-risk. Every organization which addresses screening recommendations gives strong advice to discuss in advance, before screening is initiated, these issues as we’ve discussed above. A gloved finger palpation of the prostate on a yearly basis is now not routinely advised, since it doesn’t help us find relevant prostate cancers any earlier. The recommendation for those who select screening is a yearly blood test PSA if the patient is willing to have a biopsy of the prostate if the PSA is elevated, and is willing to either be monitored or treated for prostate cancer even knowing that for the majority of men, a diagnosis of prostate cancer will not have been relevant to their health.
As previously discussed, in men with prostate cancer localized to the prostate, the risks of dying of such are low. When prostate cancer has invaded outside the prostate or has spread to pelvic nodes, many treatments can be used in addition to prostate removal, such as radiation therapy and androgen hormone blockade. Since these combination treatments are so successful, the chance of dying of prostate cancer metastasis is also close to zero in the first 5 years but can approach 20 percent by 15 years. Once prostate cancer has spread outside the prostate or pelvis, to other organs, it is life-threatening. When spread (metastatic, or Stage IV), the disease is aggressive and treatments are less effective and less well-tolerated, that the chance of dying from the prostate cancer metastasis is about 70 percent within 5 years of identification of metastasis.
There are two newer concepts regarding management of men diagnosed with prostate cancer. We’ve learned to emphasize the importance of the Gleason score (as mentioned above), localized or regional cancer, and a low PSA. The Gleason score is a numerical value applied to characteristics under the microscope, this information is provided by the pathologist in evaluating a needle biopsy of the prostate gland or by testing the entire prostate after its removal. A Gleason score of 5 or 6 is considered low risk, 7 or 8 is an intermediate risk, and 9 or 10 can be considered to be aggressive. So, if a man has a prostate cancer localized to the prostate (determined by imaging or proved by prostate removal called prostatectomy), and if the Gleason score is 5, 6 or sometimes 7, and the PSA is less than 10 ng/mL, the chance of progressing to metastasis becomes an exceedingly rare event.
With a diagnosis of prostate cancer by needle biopsy, a man can select one of two observational strategies. The first is called watchful waiting, in which case a patient can be evaluated in the office at appropriate intervals. For example, 2 to 4 times a year, and in the absence of symptoms (meaning no bone pain or weight loss and no changes in urinary habits), to not deliberately pursue any further investigation until such time as a symptom develops, if it ever does. If symptoms occur, a person can be treated with androgen blockade or radiation therapy to diminish the symptoms; if there are metastases, these treatments are unlikely to be curative. The second strategy is called active surveillance, in which serial PSAs are obtained and if they stay low, do nothing else. If the PSA rises, then repeat a prostate needle biopsy looking for an increase in the Gleason score and then the option of selecting a curative treatment.
Most organizations which give recommendations for cancer screening of men of average risk advise a discussion with their healthcare provider about the benefits and limits of PSA testing. The concern is over the high rate of overdiagnosis and its treatments although that man’s prostate cancer may not have been relevant to his health. Observational strategies once a diagnosis is made are gaining approval but still only few men and their treating clinicians have selected this pathway even though the majority may be candidates.
Talk to your primary care clinician and Urologist about this, and don’t hesitate to seek second opinions for information.