SAFETY MARGIN IN ANUS-SAVING RESECTION FOR LOW RECTAL CANCER

The length and method of measurement of the safety-margin below the rectal cancer, being of the utmost importance for its prognosis, is still under debate.The following study was designed and done for its solution.Light microscopic examination was done on 83 resected rectal cancer specimens to assess the extent of intramural invasion towards the anus.By use of a ruler,the distance between the lower tumour margin and the resection line or the dentate line was measured when the specimen was:l. freshly resected,2.after fixing in 10% formalin, and 3.after being mounted in sections. The measurements were compared. By the same method,the distance between the lower tumor margin and the intended resectyion line was measured immediately before resection.It was compared with the measurement immediately after the resection.In 83 rectal cancer specimens, the extent of intramural infiltration toward the anus was:≤0.5 cm in 75 cases (90.4%).≥l cm in 2 cases which showed highly malignant carcinomas.These 2 cases, however,should not have been indicated for anus-saving resection.In 46 fresh specimens,the tumor-resection line distances gave an average of 2.7 cm.After fixing in 10% formalin, they became shortened by 0.7 cm. And, mouting in sections further shortened them by another 0.5 cm,giving a total shortening of l.2 cm.The tumor-resection line distance in 7 of the 11 fresh specimens resected by the Dixon's operation was shortened,though never more than o.5 cm immediately the operation.In performin ganus-saving resection for the low rectal cancer, after full isolation the rectum and stretching it slightly,≥3 cm of the rectum distal to the lower tumor margin should be resected.A safety margin of more than 2.5 cm is necessary in the fresh specimen.If formalin fixed specimen is measured, the safety margin should be ≥2 cm.

LOOSENING AND LENGTHENING OF INTESTINAL TRACT AFTER RECTAL ISOLATION IN ANUS－SAVING RESECTION FOR RECTAL CARCINOMA

In low rectal cancer surgery,the section of rectum destal to the lower tumor maigin is relaxed and lengthened after fully isolation of the organ. This would facilitate the adoption of anus saving operation.Before and after fully isolation of the rectum in low ratal cancer surgery, the distance between the lower tumor margin and the anorectal line was measured by the same rectuscope introduced through the anus.The two results were compared .The average lengthening was less than 1 cm if the lower tumor marginanorectal line distance was 5 cm.It was 1─2 cm if the lower tumor margin-anorectal distance was 6 cm.It was more than 2 cm if the distance was 7─9 cm.The loosening and lengthening of the rectal canal was related to the presence of lymphnode metastasis and the skill of the operator.The lengthening was also influenced by the body build of the patient,involvement of the rectal circumference and the Dukes stage. Modified Park's operation,trans abdominosacral resection with anastormosis of rectum,and anterior resection on transpubic approach are indicated for those in whom the lower tumor margin-anorectal line distance was 5 cm The rectectomy-anastomosis in the abdominal cavity(Dixon's operation)is indicated for those in whom the lower tumor margin-anorectal line was 6 cm.If manual anastomosis is difficult,stapling device may be used. The anus saving resection is easy if the distance was 7─9 cm.