16/10/2015

BIGOSA: Prof Schnitt

Last weekend was the 4 th BIGOSA meeting.  The group has grown in strength over the last 4 years with this meting, in Durban, being the biggest so far.

The invited speaker was Prof Stuart Schnitt, a pathologist from Boston.  He gave two talks.  The first
addressed the contentious question of what is an adequate margin.  What is meant by that? Surgery for breast cancer falls into two categories: a mastectomy or a wide local excision (breast conservation).  If a mastectomy is not indicated and breast conservation is decided upon, the cancer must be removed with normal tissue around the lump.  The normal tissue is known as the margin.  What is an adequate margin?  Does removing more tissue reduce the likelihood of the cancer recurring?  It is a debate that has continued for many decades. As surgeons, we tend to assume that the pathologist's report stating that the margin is 1 mm or 5 mm or 1 cm is absolute. It is much more complicated than that!  There are many pitfalls that may occur in the processing and interpretation of the pathology.

Over the last 10 years, evidence has led us to conclude that annadequate margin is no cancer at the edge of the specimen.  There is no advantage in having a 5 mm margin over a 1 mm.  "More is not better, it is just more".

His second talk was about DCIS, ductal carcinoma in situ, pre cancer of the breast. The diagnosis of DCIS has increaed markedly since mamamograpahic screening programmes were been introduced in the 1980s.  Initially, all women were advised to have a mastectomy after the diagnosis of DCIS.  That was based on the assumption that DCIS always progresses to invasive cancer.  It was seen as a chance to prevent women getting cancer.  Once again, it is more complicated than that!  Approximately 12 % of women who die of other causes will have DCIS in their breast.  The pre cancer did not cause them a problem. They died of other causes.  How long had it been there? Conversely, DCIS may become invasive cancer fairly rapidly.  Prof Schnitt notes that whilst we have made considerable strides in understanding more about the biology and behavior of invasive cancer, little has changed in our understanding about DCIS.

The questions we need answered are:
When do we need to treat DCIS and when should we observe it?
When can we simply remove DCIS and when do we need to give radiotherapy or do a mastectomy?

The problem is that if there is a recurrence after removal of DCIS, half the time, the recurrence is an invasive cancer.  The opportunity to prevent cancer has been lost.  Clinical trials have identified women who are more likely to have a recurrence after a simple excision.  Prof Schnitt took us to the newer areas of research.  Molecular studies are being done trying to predict which types of DCIS will progress.  The focus of interest is moving from the seed ( the cancer cells) to the soil (the surrounding cells).

Is this history recurring in a new guise?  In 1889, Stephen Paget, an English surgeon wrote a paper about why some cancers metastasize and other don't.  In that paper, he said, "When a plant goes to seed, its seeds are carried in all directions; but they can only live and grow if they fall on congenial soil."

The 2 lectures given by Prof Schnitt were certainly the clearest and most enlightening I have ever heard on the subjects.  We were very fortunate to have him as our guest speaker.

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