p53 status: an indicator for the effect of preoperative radiotherapy of rectal cancer

Surgeon influenced variables in resectional rectal cancer surgery

PURPOSE

Surgeon influenced variables in rectal cancer surgery were assessed.

METHODS

The literature was reviewed to discuss technical and educational issues that may affect the outcome of surgery for rectal cancer. Particular attention was paid to recently debated topics such as adjuvant therapy, colonic J-pouches, total mesorectal excision, and surgeons' training.

RESULTS

In some selected cases, transanal techniques with or without neoadjuvant or adjuvant therapy have improved the success of local excision. The biology of rectal cancer has begun to be understood. However, until a more complete understanding with an appreciation of therapeutic implications has been arrived at, surgeon influenced variables will continue to be of paramount importance. Multiple studies have shown tremendous surgeon variability in the outcome after rectal cancer surgery. Some of the variables that have been shown to be important include tumor-free distal and lateral margins, a total mesorectal excision, and an appropriate anastomosis. It has been well demonstrated that proctectomy with straight coloanal anastomosis compromises function as compared with preoperative levels or healthy controls. These deficiencies are further exacerbated by adjuvant therapy. Significant functional improvements, particularly in the first 12 to 24 months after surgery, have been achieved with use of colonic J-pouch.

CONCLUSION

There are many ways by which the surgeon can optimize curative resection for rectal cancer. Appropriate distal and tumor-free lateral margins with total mesorectal excision should be the goals for all tumors in the lower two-thirds of the rectum. Reconstruction should be performed, whenever technically possible, by a colonic J-pouch. Surgeons should be cognizant of their own practice patterns, volume, capabilities, and very importantly results. These results should be audited frequently and willingly shared with patients.

Can p53 alterations be used to predict tumour response to pre-operative chemo-radiotherapy in locally advanced rectal cancer?

PURPOSE

To examine whether p53 tumour suppressor gene alterations can be used to predict tumour response to pre-operative chemo-radiation in locally advanced rectal cancer in terms of reduction in tumour size and local failure.

METHODS

p53 alterations were studied in pre-treatment biopsy specimens of rectal carcinomas from 48 patients by immunohistochemistry (IHC) and polymerase chain reaction/single strand conformation polymorphism (PCR-SSCP) gene mutation analysis. Pre-operative pelvic radiotherapy was delivered with four fields, 45 Gy to the ICRU point in 25 fractions over 5 weeks. A radio-sensitising dose of 5-fluorouracil (500 mg/m(2)) was delivered concurrently for 6 days of the 5-week schedule (days 1, 2, 3 and days 22, 23 and 24). Total meso-rectal excision was planned 4 to 6 weeks from completion of pre-operative treatment. Response to therapy was assessed by macroscopic measurement of the surgical specimen by a pathologist who was unaware of the pre-treatment tumour size or of the p53 status.

RESULTS

IHC evidence of p53 protein accumulation was found in 40% of tumours, p53 gene mutation in 35% and p53 alteration (either or both changes) in 46%. The average reduction in tumour size was 53% in the group with 'wild-type' p53 (IHC-/SSCP-) and 63% in the group with altered p53 (either IHC+ or SSCP+; P=0.18). No significant differences in tumour size reduction or local failure were observed in the groups with p53 overexpression or p53 mutation compared with normal.

CONCLUSIONS

p53 alteration detected by IHC or SSCP analysis is not a clinically useful predictor of local response to pre-operative adjuvant therapy in advanced rectal carcinoma.