Rectal cancer : staging, radiotherapy and surgery

Abstract

In Sweden, about 1800 patients are annually diagnosed with adenocarcinoma of the rectum. Surgery remains the major primary treatment. Adjuvant radiotherapy and total mesorectal excision (TME) are two major achievements in rectal cancer treatment during the last two decades. The subsequent improvement in local control and survival with a reduced need for permanent colostomies is of great benefit for the patients. With the development of new treatment strategies for rectal cancer, including neoadjuvant treatment modalities, the necessity and importance of accurate preoperative staging has increased.

The Stockholm Colorectal Cancer Study Group (SCCSG) was set up in 1980 with the aim of improving outcomes in patients with rectal cancer. Between 1980 and 1993, SCCSG completed two prospective randomised trials which evaluated the efficacy of preoperative radiotherapy (the Stockholm I and Stockholm II Trials). In 1994 the group initiated a collaborative education project, including surgical and pathological workshops, to introduce the concept of TME to colorectal surgeons and pathologists in Stockholm (the TME Project). Since 1995, all patients with colorectal cancer in Stockholm have been included and prospectively registered in a regional treatment programme initiated by the SCCSG (the Regional Treatment Programme Register).

This thesis is based on patients from the Stockholm I and II Trial and the Regional Treatment Program and assesses the prognostic significance of staging, radiotherapy and surgery in patients with rectal adenocarcinoma with special focus on outcome in relation to preoperative short-term radiotherapy, TME based surgery, magnetic resonance imaging (MRI) and the individual operating surgeon.

It is concluded that preoperative radiotherapy with 5x5 Gy reduces local recurrence rates with more than 50% and may improve survival. This beneficial effect is seen both with conventional surgical techniques and TME based surgery. Preoperative radiotherapy may increase postoperative morbidity and mortality in subgroups of patients and should be given with caution to patients with symptoms of severe arterioclerotic disease.

The TME Project encouraged and enhanced a major shift in rectal cancer surgical practice in Stockholm with an increased centralisation and specialisation. As a result, local control and cancer specific survival was significantly improved. In addition, the rate of APRs declined. TME based surgery demands surgical skill, which can be achieved by participation in education programmes and increased personal training and experience. Patient outcome after surgery is related to the individual surgeon and is mainly related to the surgeon s case volume, with better results obtained in patients treated by high-volume surgeons. A tumour-involved circumferential resection margin (CRM) is of strong prognostic value and may be detected on preoperative MRI. If an involved CRM is identified, this is predictive of distant metastases and survival.

The surgeon s postoperative statement regarding whether complete or incomplete tumour clearance was achieved at the operation is of strong prognostic significance with regard to recurrence and survival. An ambiguous report in this respect should be regarded as an indicator of incomplete clearance and of non-curative surgery. This highlights the importance of a clear definition of curative surgery.

With current protocols combining standardised preoperative staging, modern radiotherapy techniques and TME based surgery, low rates of local recurrence should be achieved. The challenge for the future is to prevent and treat distant metastases and to further improve survival.