A resection margin or surgical margin is the margin of apparently non-tumorous tissue around a tumor that has been surgically removed, called "resected", in surgical oncology. The resection is an attempt to remove a cancer tumor so that no portion of the malignant growth extends past the edges or margin of the removed tumor and surrounding tissue. These are retained after the surgery and examined microscopically by a pathologist to see if the margin is indeed free from tumor cells. If cancerous cells are found at the edges the operation is much less likely to achieve the desired results. Residual tumour at the primary site after treatment is classified by the pathologist as :
R0 - no cancer cells seen microscopically at the primary tumour site.
R1 - cancer cells present microscopically at the primary tumour site.
showing a positive cauterized surgical margin in an adenocarcinoma. H&E stain. The Margin Status following tumour resection :
Negative margin: No tumour at the margin.
Microscopic positive margin: Tumour identified microscopically at the margin.
Macroscopic positive margin: Tumour identified grossly at the margin.
Margin not assessed.
The size of the margin is an important issue in areas that are functionally important or in areas for which the extent of surgery is minimized due to aesthetic concerns. The desired size of margin around the tumour can vary. In resections for breast cancer, there appears to be a difference between European and American radiation oncologists, with the former preferring larger margins of over 5 mm. Apart from traditional methods looking at stained "shaves" or smeared and stained imprints, more recent techniques used to assess margins include x-rays with compression, frozen specimens, and new techniques such as optical coherence tomography and quantitative diffuse reflectance spectroscopy.
Definition
Surgical margin in a surgery report defines the visible margin or free edge of "normal" tissue seen by the surgeonwith the naked eye. Surgical margin as read in a pathology report defines the histological measurement of normal or unaffected tissue surrounding the visible tumor under a microscope on a glass mounted histology section. A "narrow" surgical margin implies that the tumor exists very close to the surgical margin, and a "wide" surgical margin implies the tumor exists far from the cut edge or the surgical margin. Narrow surgical margin using the bread loafing technique suggests that residual cancer might be left due to false negative error. A surgeon often will perform a second surgery if a narrow surgical margin is noted on a pathology report.
This determination is made with the full understanding of "false negative error" intrinsic in the bread loafing technique of histology. The higher the false negative error is, the higher the recurrence rate of a cancer or tumor at the surgical margin. This is due to the misreading of a pathology specimen as being clear of residual tumor when there is actually residual tumor left where the specimen was not cut and mounted on the histology slide. The "false negative error" is very low in the CCPDMA method of histology processing, and can be very high in the bread loafing method of histology processing. In the bread loafing method of processing, one will note a high false negative error rate with narrow surgical margin; and one will note a low false negative error with a wide surgical margin Surgical margin has a much less significant effect on the false negative error rate of CCPDMA methods, allowing the surgeon to routinely use very narrow surgical margins.
