With Mr. Bidens recent prostate cancer diagnosis, a lot of posts are using terms which may not be familiar to the average person. Stage, Grade, and Gleason score are all different indicators. Staging reflects how far the cancer has already spread, and presented as Stage I-IV (in many cancers there are also letters as modifiers), with higher numbers being worse. The exact spread that each cancer needs to reach a specific stage varies from cancer to cancer. It takes into account the size of the tumor, the location and number of lymph nodes to which it has spread, and whether it has established itself in organs not adjacent to the original tumor. Stage IV is usually spread to distant organs such as the liver, or bones. The highest value for prostate cancer is IVb.
Grade is how abnormal the individual cells appear under a microscope. The more abnormal they look, the faster most cancers are likely to progress. Think of it as a care driving toward a cliff—the Stage is how close the car is to the cliff–how far it has already driven. The grade is how fast the car is going. It may be far from the cliff, bit if it is going fast, it will reach it sooner. However, different types of cancer spread at different rates even if they are the same grade.
Gleason Score is a system used specifically in prostate cancer. In a prostate biopsy, usually several cores are taken from different locations of the prostate that look like they may have cancer. The grades of the two cores that occur most commonly are added together to give a score of 1-10. A higher score is worse. Mr. Biden could not have had a Stage 9 cancer, but it is possible to have a Gleason score of 9.
PSA is prostate-specific antigen. It is usually elevated in prostate cancer, but its routine use in men without symptoms has been controversial. This is because it is often elevated in men without prostate cancer and it is not elevated in some men with prostate cancer (estimates vary of the numbers, but it is clear that there are many false positives and some false negatives). The value of the test has also been questioned because prostate cancers are often indolent, growing so slowly that even though there may be a tiny spot of cancer, it may grow so slowly that it will never bother the patient during his lifetime. The United States Preventive Services Task Force has changed its recommendations over time regarding this test. It was once recommended for nearly all men over fifty. Later it was considered to have more harm than benefit in most men. Currently guidance is that the decision to order it should be based on discussion with patient, taking into account individual risk factors and preferences in men 50-69.
For men over 70, PSA is not recommended at all. Most (possibly all) men will develop small areas of prostate cancer after that age, but because the most of these grow so slowly, it is not likely that the man will live long enough for it to ever bother him.
There are other factors used in evaluating PSA results besides the absolute total PSA, but so far I have not seen any of them mentioned in the media, so will not discuss. Digital rectal exams have been used in the past, but are less sensitive than PSA. It one is done, usually PSA is also recommended.
The above statements about PSA and DRE apply only to men without symptoms and without specific personal risk factors. If there are symptoms that suggest a prostates cancer, or if the patient is at higher-than-average risk, it is usually advised to do testing.
While prostate cancers usually progress slowly, this is not true in all cases. As Mr. Biden is 82 years old, per USPSTF guidelines, he should not have been screened for prostate cancer in twelve years. This could be adequate time for him to have had screening before the age of 70 but developed the cancer after he had “aged out” of routine screening. It is also possible that his cancer is one of the 5-15% of prostate cancers that are not associated with elevated PSA.
(This is just a brief overview presented in the hope of giving some context to allow nonmedical readers to understand what they see in the media. I am a family medicine physician. I am sure that urologists and oncologists can provide more detail).
