Pet Forum / Miscellaneous / Animal Health / February 2005

Whoops meant peanut....still small relative to the size of a lab....

Deborah, DVM

.............Deb, I read a study a long time ago that mentioned that success
in MCT was a sufficient margin on the first surgery and the expertise of the
surgeon (i.e., the more surgeries of this kind the doc had done the better).
So if you took a margin comparable to a Grade II tumor, then that might be
true.

http://www.hammocksvet.com/NewsArticles/PTCancer.htm
"A biopsy or tissue aspirate should be done if it will change the outcome
of treatment or surgery. For example, a mast cell tumor requires 1 ½ inches
of tumor free tissue to be taken to ensure 'clean margins'; normal surgical
rules recommend a ¼ inch margin. Without a pre-operative tissue aspirate
your dog may need two operations to remove the entire tumor; if we do an
aspirate pre-op the surgeon can remove it all the first time. In stitches
terms, a pencil eraser sized non mast cell tumor would take about 4
stitches; the same sized mast cell tumor would take about 12 stitches! (FYI
mast cell tumor is the most common skin tumor in dogs and it is very
unpredictable)."

http://cliniciansbrief.com/cb/capsules/may04capsules.asp
Surgical Margins for Cutaneous Mast Cell Tumors
Tumors were excised routinely, fixed in formalin, graded, and histologically
examined for neoplastic mast cells in the margins. All grade 1 tumors were
completely excised at all margins. Seventy-five percent of all grade 2
tumors were completely excised at the 1-cm margin, and 100% were completely
excised at the 2-cm margin. Grade 2 tumors located on the hind limbs of 2
dogs were excised with a complete but close (within 1-mm) deep margin. Their
results suggested that a 2-cm lateral margin with a deep margin of 1 fascial
plane is sufficient for complete excision of grade 1 and grade 2 MCTs.  In
another retrospective study evaluating the success of surgical treatment for
70 MCTs affecting the trunk and limbs of 56 dogs (head or neck tumors were
not included in either study), Baker-Gabb and coworkers found that the most
significant risk factor for local recurrence was histologic tumor grade.
Fine-needle biopsy yielded correct MCT diagnosis in 96% of the cases
(histologic tumor grade can be expected to be consistent regardless of MCT
size and location). In this study, grade 3 tumors were significantly more
likely to be incompletely excised than grade 1 or 2 tumors; however, wide
margins were not significantly more likely to achieve complete removal of
grade 3 tumors, hence the authors' recommendation that the invasiveness of
surgery be decided on the basis of histologic or cytologic examination.

Not to mention the issue of seeding with sectional biopsy:

http://www.vetinfo4dogs.com/dmulticancer.html
"There is some evidence that certain tumors can be seeded to other
areas through fine needle aspirate or other biopsy techniques but I have
not seen much information about tumor potentiation or activation as a
result of biopsy. In general, the risk of seeding is pretty low with a fine
needle aspirate but has definitely been observed with surgical biopsy
techniques and with partial removal of tumors."

buglady
take out the dog before replying