Dr. Richard Rinn - Pathologist

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Dr. Rinn began his talk by outlining what a pathologist does. Most people hear the term pathologist and think of autopsies. That's true but it's a relatively small percentage of the work that he does. Most of his time is spent at a microscope, looking at slides of material that comes out of the operating room and the ambulatory day care and making diagnoses of what he sees.

Dr. Rinn emphasized that in our examination by the doctor, we should have a digital rectal examination (DRE). He said the reason for this is because he can feel the prostate quite well through the wall of the rectum, whether it is enlarged, whether it's soft or hard, whether there are any nodules or anything suspicious for cancer. He stressed that most prostatic pathology is benign. It's only the minority that's actually malignant in nature. And it's most frequently the benign disease that causes the urination problems and causes the enlargement of the prostate, etc. Nowadays it's easy to stick a needle through the rectal wall and take samples of prostatic tissue out and send them to the lab so that they can examine them.

According to Dr. Rinn, the role of the pathologist includes dealing with the actual treatment. Once they've established that there is cancer and the surgeon has decided to do a radical prostatectomy, the pathologists have an important role in helping him to do the operation and helping him to assess the success of the operation.

Part of the reason they're picking up more cancers now than they used to, is that the old method of going up into the urethra and taking samples, made it less likely to find the cancer. Using the biopsy needle through the rectum wall enables them to take samples from the more likely parts of the prostate that the cancer would be developing. Dr. Rinn used slides to show us what the cancer looks like in the prostate. He first showed a slide of a benign prostate demonstrating the orderly architecture of normal tissues and a nice arrangement of the cells. He asked us to keep that view in our mind in order to compare it with what cancer looks like. He then showed a slide showing prostatic cancer in a well differentiated gland. He pointed out the cancer tends to be smaller cells, crowded and haphazard in nature. They tend to be darker, picking up more of the stain they use to identify them. Dr. Rinn explained what he meant by well-differentiated: the tumour itself looks very much like a normal prostate gland but there are sufficient changes in it for them to make a diagnosis of malignancy.

He next brought up how the pathology department arrives at a Gleason grade. He charted the differentiation degree of a tumour for us. A well differentiated tumour is on the low end of the scale. A poorly differentiated tumour begins to look very, very wild, in fact, in the process of growing, it no longer looks like the original tissue from which it arose. This would be on the high end of the scale. Well differentiated tumours tend to do better, they're less aggressive, they require less therapy. Tumours which are poorly differentiated tend to do more poorly and require more aggressive therapy. The Gleason Score tries to give a numerical value, a more scientific value, to how well differentiated a malignancy in the prostate is. We assign a number of one to five depending upon how well differentiated that tumour is. If its very well differentiated, we say it is one. Very poorly differentiated, we say its a five and in between in the spectrum and we say it's from one to five. In order to give a grading from one to ten, we look at the two most prominent patterns within the tumour, so we combine those two scores. For instance, if one component is very well differentiated and it's a two but the other component is a five, then the total Gleason Score out of ten is a seven. Seven out of ten is very important in trying to decide which therapy is required. Very low Gleason Scores might not require any therapy. According to Dr. Rinn, if you've got a four or a three, you might not need any treatment at all. However, if you've got a seven or a nine then that's something that has to be treated aggressively. So this is one of the things pathologists do, they grade the tumour. They try and give the surgeon an idea before he does his operation, how well differentiated the tumour is and how aggressive the tumour is likely to be, based on this assessment. Dr. Rinn said that the most important thing that they do as pathologists, is make a diagnosis of cancer. That is, when they say to the surgeon, "This person does not have a benign disease in the prostate, this person has cancer," that then gives the surgeon the ability to go ahead and plan treatment.

The next stage of their interaction with the surgeon, now moves into the treatment phase as they influence the surgeon to help him make better decisions while he's doing the surgery. The surgeon makes an incision in the abdomen, goes down into the pelvic region and retracts the bladder out of the way so that he can see the prostate. In the process of doing that he frequently looks for things called the lymph nodes which are in same general region as the prostate. These are little collections of white blood cells which are a very important part of the body's immune system. They're also not only very important in fighting off infection, they also play an important role in fighting off cancer and the spread of cancer. However, some of the first places the cancer spreads to after leaving the prostate is to these lymph nodes. So what the surgeon will very frequently do during the course of this operation is he will hunt around in the abdomen in the pelvis and he will look for lymph nodes that are close to the prostate and dissect them out. Then he will send them to Dr. Rinn so that he can look at them and tell whether or not the cancer has spread outside the prostate. If cancer has spread to the lymph nodes already, then the urologist will probably decide not to go on with the operation and suggest other treatments such as radiation or hormones. If we don't find any cancer in these lymph nodes, that's a good prognosis as it means that the cancer probably hasn't spread beyond the prostate gland and if the surgeon takes out the prostate he probably will remove all the cancer.

The final segment of what a pathologist does, is when they have the prostate gland in front of them after it's been removed. They have to give the urologist all the information that he requires to give a prognosis which is the likely outcome of this particular cancer. The pathologist gives him the information which will tell him whether or not further therapy is required. They cut up the prostate into manageable size pieces and treat the pieces with preservative type chemicals then put it into a machine which permeates the tissue with a wax-like substance which then allows them to slice it very thin ñ 4/1000ths of a millimeter. They then mount these thin "wafers" onto glass slides for viewing under the microscope. During the course of the day they may make 250 slides of tissue taken from various operations. At this point ñ viewing the slides ñ they look for such things as the degree of differentiation. They try to re-assign a Gleason Score. From the biopsy they were only basing the score on a little piece of tissue, now they have the whole prostate to evaluate. They try and give a picture of how much of the prostate gland is cancerous, because the volume of the tumour is actually something which can often predict how well the patient is going to do. They try to tell if only one half of the gland is involved in cancer, as opposed to both halves, which is another prognostic factor. Very important is to look at the margins, the point at which the urologist has cut around the prostate, to determine whether the cancer had already spread outside the prostate before the surgery was performed. If this is the case then it may require that the patient go through radiation to try to deal with any microscopic disease that might be left behind. All of these things are put into a report so that the urologist has a permanent record of it and so that he knows exactly the characteristics of the tumour in this particular patient.

Here are a few of the many questions posed to Dr. Rinn and his responses

Q. How big are the lymph nodes? I always thought were microscopic.

A. Some lymph nodes are very small but some of them in the male pelvic area can be about five or six centimeters long. Often what happens is they get large, not because there's tumour inside, but there's fat. For some reason normal, benign fat gets inside them.

Q. I thought the lymph nodes were receptacles for white blood cells, which can fight infection. But now you're taking these out. Isn't that dangerous?

A. We have found out that these diseases (prostate and breast cancer) are systemic which means they can spread from a very early stage and these lymph nodes don't necessarily provide much defense but they can give us very useful information about the stage of the disease at the time of the operation. In other words, what amount of tumour has spread to those lymph nodes is much more important to know than having those lymph nodes in place after the operation.

Q. I had several biopsies which showed no cancer. I went to another hospital at the recommendation of another urologist and their biopsy found cancer. How come?

A. That's not entirely uncommon. These biopsies are less than a millimeter in most cases, even though we're taking up to eight or twelve of these in some cases, that still represents well less than one percent of the total prostate. So one of the problems is sampling. If the tumour, for instance, is very local you might just find it by accident. The surgeon who's doing the biopsy doesn't really know where the tumour is. That's the reason he takes so many of those biopsies The more that you take the more likelihood that you'll pick up some of that cancer. You always get, in the end, a lab test which shows some false negatives, which happened in your case, probably those first two were false negatives. Sometimes we may pick up things which are not cancer but which may make us suspicious that cancer may be lurking in the background. Our knowledge has improved dramatically in the last ten years. There's something call PIN which is not cancer but is a change in the glands which we can see and when it's severe enough it indicates to us that these people are at an increased risk of getting cancer some time in the fu ture, or they may already have cancer somewhere else in the gland which has not been picked up by the biopsy.

Q. What's the chance of the biopsy actually creating a route for the cancer to escape from the prostate?

A. That's always been a question in the past and always been a worry amongst the surgeons. Generally speak ing, I think the consensus now is that is a very low probability. These biopsies have been extremely useful and the benefit very much outweighs the tiny potential for spreading the tumour.