In our study, we evaluate similarities and differences in neoadjuvant treatment of rectal cancer according to radiotherapists, medical oncologists, and surgeons. The ultimate goal for neo-adjuvant treatment is CR which can be achieved in different treatment models for different risk stratification.
In patients who had pCR after neoadjuvant CRT, long-term outcome was reported to be excellent with less local and distant recurrence. The pCR rates were considered to be between 15-27% after neoadjuvant CRT and delayed surgery. Although pCR is considered to be good prognostic factor 5 years OS is still the main determiner in this patient group. Valentini et al showed that 2 years’ DFS considered being a better prognostic factor than pCR in rectal cancer. The clinic utility of the pCR is still controversial and needs to be investigated. In contrast to other studies, our study population was formed by high numbers of CR patients, which established a valuable source of information in this patient group. Also, the study may be valuable for future meta-analysis.
The response to the CRT may have a relation with the delay of surgery. The first strong study was the Lyon study showing six weeks of delay until the surgery increased the pCR in patients compared to two weeks. In a large study, 10-11 weeks delay of surgery after neoadjuvant CRT have the highest pCR rates. No increased response rates were observed with waiting longer than this time interval. retrospective data reported prolonging the interval between CRT and surgery increasing the CR rates. Moore et al and Tulchinsky et al. declared waiting more than 7 weeks increased the CR rates significantly.[21, 24] Another study confirmed the prior studies with an eight-week waiting period. The CR rates were doubled with a longer interval. This data was strengthened with a meta-analysis that was performed in 2005. Better outcomes and CR rates were reported without significant morbidity. on the other hand, waiting longer than 11 weeks did not result in a favorable outcome. Comparing 7 weeks to 11 weeks interval between CRT and surgery was failed to show increased CR rates. Similar to our results in a Turkish population study there was no difference between 4 and 8 weeks’ waiting period between CRT and surgery. In our study, we showed most of the participants had preferred 7-8th and 11-12th weeks were the optimal operation period. Although the hypothesis of a longer waiting period increased the CR rates the optimal duration of the interval is not firmly established. A very small subset of the study population declared, they prefer the perform surgery more than the 13th week. Also, the effect of genetic and racial differences on tumor response is not known. The confirmative results of Saglam et al. may strengthen the racial effect on tumor response in the Turkish population.
The second controversial area is adding neoadjuvant chemotherapy to the treatment plan. Also, the optimal protocol and number of cycles are questionable. Garcia-Aguelar showed that adding two cycles of chemotherapy including 5-FU, oxaliplatin and leucovorin had increased the pCR rates up to 38%. In our study, more than 20% of the patients received neoadjuvant chemotherapy. There was no effect on the prognosis in terms of OS. Also, the chemotherapy protocols and cycles were not eligible. The neo-adjuvant chemotherapy preference was significantly high in medical oncologists when compared with surgeons and radiotherapists.
The selection of the treatment strategy is mainly dependent on primary risk factors and post-surgical margins. In the very-low risk group which is evaluated with endoscopic ultrasonography, the main treatment option is considered to be primary surgery. In patients with low-risk short-course, RT and conventional long-course radiotherapy with concurrent chemotherapy have similar results. However, recent data published if the post-operative margin is at risk conventional treatment had similar results with short-course radiotherapy followed by pre-operative oxaliplatin including chemotherapy. The difference between medical oncologists and other groups may depend on altered recurrence concerns in groups.
The study was a survey study that tries to evaluate the pitfalls but was still lacking revealing most of the unidentified parts in daily practice. The participants from radiotherapists and surgeons were lesser compared with medical oncologists which made comparison hard between groups. Also, high numbers of young participants in the medical oncology group may affect the results.