I  am asked by men and women why Gleason scores sometime change from the biopsy after surgery. Below is an explanation from Paul Carpenter that put it in easy to understand terms. He said he would be happy if others used his analogy. This is what he said:

Hi Sue,

Here’s an analogy to explain why the Gleason sum determined by the pathology report on the entire gland might differ from the biopsy result.

Let’s say that an office memo that is “normal” is a sheet of paper with uniform typewriting on it. A memo that is “abnormal” could be different in one or more ways. For example, it might have words typewritten in a different font (grade 1), or a handwritten note neatly printed in black ink (grade 2), or a handwritten note scrawled in blue ink (grade 3), or a wet juice stain (grade 4), or an obliterating and still-smoldering scorch (grade 5). The various abnormalities could appear together, and the extent of each might be tiny, small, medium, etc.

From the sheet of paper, use a hole punch to obtain eight or twelve small samples, mainly from the posterior half. These are biopsies. If the
abnormalities are very extensive (regardless of seriousness), it is quite probable they will show up in at least one of the samples. But there is a risk that a small abnormality was missed by the sampling, and that the sampling was unable to probe the anterior half very thoroughly.

The pathology report lets you scrutinize the entire sheet of paper, permitting the best possible assessment of the seriousness and extent of
each abnormality. Using the examples above, a Gleason sum of 3+4 would mean that of the various abnormalities, the majority are blue-ink handwriting; there’s a small juice stain; and there’s no scorching at all.

/Paul in Los Angeles

Thank you to Paul.