Initial Treatment of Rectal Cancer

Local recurrence has different characteristics depending on the original type of "curative" surgery. Furthermore, the surgical technique directly influences the local recurrence rate in patients with potentially curable disease. The main surgical modalities in the treatment of rectal cancer depending on the number of various factors are: anterior resection (AR), abdominoperineal resection (APR), local excision and, sometimes, Hartmann's procedure.

Regardless of the type of "radical" procedure, some basic, well established, rules of rectal cancer surgery are to be followed: total mesorectal excision (TME), distal clearance, high ligation of IMA, excision of the lymphovascular "baring" segment, preservation of the vegetative pelvic nerves. Together with these rules we will address another important factor for predicting local recurrence - circumferential margin of resection (CRM).

TME is the well established "gold standard" of rectal cancer surgery, and it includes a meticulous sharp dissection of the avascular "holy" plane between visceral mesorectal fascia and endopelvic fascia under direct vision [13,14].

Distal clearance has been the subject of different discussions and speculations over the last few decades, concerning the radicality of the procedure. There is no question that the "5 cm rule" is, only a historical fact now. The works of Madsen and Williams [15,16] showed that, distally, tumour rarely spreads. Thanks to that, sphincter-saving procedures became possible, provided there were no technical limitations. Even low intersphincteric resections showed no increase in local recurrence when compared to APR [17].

CRM is the most important predictive factor in genesis of local recurrence. Involvement of CRM by tumour in rectal cancer is the only pathologic variable that independently influences both survival and local recurrence. A tumour that has a lateral clearance less than 1 mm has a much greater probability of recurrence (3.5 times greater risk). It also doubles the risk of death. The accuracy of CRM status in predicting the likelihood of local recurrence is 75%. The percentage of local recurrence was 38.2 vs. 10% when comparing involved and uninvolved CRM margins, respectively. Five-year survival was also influenced by CRM margin (72 vs. 29% when comparing unin-volved and involved CRM margins) [18-21].

Local recurrence in patients who underwent AR can be anastomotic or localised elsewhere in the pelvis. Anastomotic recurrence rarely originates from the mucosal suture line, as may seem logical, but it originates from the wall of the bowel and is often peri-

Fig. 1. NMR scan of an anastomotic recurrence after incomplete TME

anastomotic [22]. A "good" aspect of this type of recurrence is that, in contrast to APR, it provides more options for follow-up (digital, endoscopical examination, biopsy if necessary and it can become symptomatic earlier). The reasons for local recurrence in this type of operation can be found in the biology of the tumour, the stage of the disease and in technical aspects of the surgical procedure. The stage of the disease is, perhaps, the most illustrative: stage I of the disease, according to TNM classification has 5-year recurrence rate of around 10%; stage II, approximately 24%; and stage III about 41% [23].

Some Authors [5,24] report much better results of salvage surgery in the group of patients treated in other institutions, where well known oncological principles (TME) of the surgery of the rectum were not completely conducted. This was explained with the longer period of time needed for tumour to infiltrate the surrounding structures, in the case of incomplete mesorectal excision (Fig. 1). The infiltration of these structures makes any attempt at salvage surgery much more difficult, and sometimes impossible. Nevertheless, symptoms of the recurrent tumour within the pelvis after the initial operation with incomplete TME occur much faster than in those with TME [8,14, 25].

Salvage surgery after APR is always more difficult [13, 26], and the percentage of local recurrence is much higher [27]. Curative salvage surgery is possible in a significantly lower number of cases. There are several factors that contribute to this. Usually, patients who undergo this type of operation have

Fig. 2. CT scan of local recurrence after APR, localised in the place of previous tumor, not infiltrating the surrounding structures

larger tumours in more advanced stages. Furthermore, surgical manipulations are much more limited in attempted salvage surgery and normal anatomy is much more violated. Also, follow-up of these patients is much more difficult [13]. Physical examination is not easily feasible. In women, vaginal examination (especially endovaginal endosonography) is often very useful in detecting local recurrence; in men the only means of follow-up are radiological methods (CT, NMR, PET scan) (Fig. 2). Also, the asymptomatic period in these patients is much longer (no apparent bleeding or obstruction).

Salvage surgery after local excision is not uncommon. Different studies report a rate of salvage surgery that ranges from 22 to 100% [28-30]. For patients in stage I of the disease, local excision, in recent years, has increasingly become the therapy of choice. T1 and T2 tumours can be treated with local excision but only in certain strictly defined indications. T2 tumours have a much greater risk of local lymph node involvement, thus are much more amenable to locoregional recurrence, and are reserved for patients that are not in a condition to undergo "radical" treatment. Despite all precautions [31], estimated 5-year local recurrence rate is around 28% compared to a much lower percentage after AR in the same stage of the disease. Immediate salvage surgery is mandatory if histopathology results are unfavourable. Poor prognostic factors in pathohis-tology report are: tumour invasion of muscularis propria, positive margins of resection, poor differentiation or lymphovascular invasion. The results after immediate salvage surgery are much better than in surgery for already existing local recurrence [32].

If pathology results are favourable, close follow-up is mandatory (every two months for 3-4 years, occasional endorectal ultrasound (ERUS)). It should be noted, however, that results after this type of salvage surgery are less favourable than after initial "radical" surgery [33]. Though salvage surgery may appear futile, around 50% of patients with local recurrence have a solitary tumour inside the pelvis, and they are candidates for a "second look" procedure. However, the number of patients that can be resected for a cure is less than 50% (between 30 and 40%) and median survival of these patients varies from 21 to 36 months [34-36].

PRT is very important in the treatment of distant rectal cancer. After PRT, combined with TME, the local recurrence rate is significantly lower. In the Dutch trial [37], excellent results were achieved concerning local recurrence. After TME alone, 2-year local recurrence rate was 8.2%, and after TME combined with PRT, 2-year local recurrence rate was 2.4%. However, a number of studies [38] showed that survival after local recurrence in patients treated with PRT was reduced. This is explained by the fact that local recurrences after PRT may be treated less aggressively, because maximal dose radiotherapy is no longer possible as part of multimodality treatment. It is also stated that the recurrences occurring after PRT are frequently associated with distant metastases.

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