Current controversies in neoadjuvant chemoradiation of rectal cancer

Pathological Complete Response After Neoadjuvant Therapy in Rectal Adenocarcinoma: a 5-Year Follow-up

Neoadjuvant therapy is the gold standard treatment of locally advanced rectal cancer. It may induce complete sterilization of tumor cell and decreases its local recurrence rate. While 15–20% of patients were found to have pathological complete response (pCR) with combined multimodal therapy, Asian data were generally scarce. pCR rate can indicate the suitability of applying the “watch-and-wait” strategy, which advocates deferment of surgery that can alleviate surgery-associated morbidity.To determine the percentage of pCR of rectal cancer after neoadjuvant therapy. Patients diagnosed with rectal cancer underwent treatment from 2013 to 2017 were retrieved retrospectively. Demographic data, tumor localization, pre- and post-operative pathological reports, neoadjuvant therapy, and pCR status were collected from patients’ records. A total of 242 out of 259 patients were treated with definitive rectal surgery. Mean age was 67.1 years old. Chinese ethnicity and male gender were predominant (n = 131, 54.1% and n = 146, 64.3% respectively). More than half (n = 124, 51.2%) had tumor located at mid or low rectum. Histologically, moderate differentiated adenocarcinoma was predominant (n = 227, 93.8%). Merely half (n = 123, 50.8%) of the patients received neoadjuvant chemoradiation therapy, but only 12 (9.8%) had a pCR. From follow-up on these 12 pCR patients, most had 2-year disease-free survival but 1 (8.3%) of the pCR had distant metastasis within 1-year post-surgery. The pathological complete response rate in our center was lower than reported. Stringent patient selection with close follow-up for patients should be carried out if the “watch-and-wait” strategy is implemented in our population.

Neoadjuvant therapy in pancreatic cancer: a systematic review and meta-analysis of prospective studies

There is a strong rationale and many theoretical advantages for neoadjuvant therapy in pancreatic cancer (PC). However, study results have varied significantly. In this study, a systematic review and meta‐analysis of prospective studies were performed in order to evaluate safety and effectiveness of neoadjuvant therapy in PC. Thirty‐nine studies were selected (n = 1458 patients), with 14 studies focusing on patients with resectable disease (group 1), and 19 studies focusing on patients with borderline resectable and locally advanced disease (group 2). Neoadjuvant chemotherapy was administered in 97.4% of the studies, in which 76.9% was given radiotherapy and 74.4% administered with chemoradiation. The complete and partial response rate was 3.8% and 20.9%. The incidence of grade 3/4 toxicity was 11.3%. The overall resection rate after neoadjuvant therapy was 57.7% (group 1: 73.0%, group 2: 40.2%). The R0 resection rate was 84.2% (group 1: 88.2%, group 2: 79.4%). The overall survival for all patients was 16.79 months (resected 24.24, unresected 9.81; group 1: 17.76, group 2: 16.20). Our results demonstrate that neoadjuvant therapy has not been proven to be beneficial and should be considered with caution in patients with resectable PC. Patients with borderline resectable or locally advanced disease may benefit from neoadjuvant therapy, but further research is needed.

Differential effects of patient-related factors on the outcome of radiation therapy for rectal cancer

OBJECTIVE

The objective of this study was to investigate whether cancer specific survival in rectal cancer patients is affected by patient-related factors, conditional on radiation treatment.

METHODS

359 invasive rectal cancer patients who consented and provided questionnaire data for a population-based case-control study of colorectal cancer in Metropolitan Detroit were included in this study. Their vital status was ascertained through to the population-based cancer registry. Hazard ratios (HR) for cancer specific and other deaths and 95% confidence intervals (CIs) were calculated according to selected patients' characteristics, stratified by radiation status, using joint Cox proportional hazards models.

RESULTS

A total of 159 patients were found to be deceased after the median follow-up of 9.2 years, and 70% of them were considered to be cancer specific. Smoking and a history of diabetes were associated with an increased probability of deaths from other causes (HR 3.20, 95% CI 1.72-5.97 and HR 2.02, 95% CI 0.98-4.16, respectively), while regular use of non-steroidal anti-inflammatory drugs (NSAIDs) was inversely correlated with cancer-specific mortality (HR 0.50, 95% CI 0.30-0.81). Furthermore, the associations of smoking and NSAIDs with the two different types of deaths (cancer vs others) significantly varied with radiation status (P-values for the interactions= 0.014 for both). In addition, we observed a marginally significantly reduced risk of cancer specific deaths in the patients who had the relative ketogenic diet overall (HR=0.49, 95% 0.23-1.02).

CONCLUSION

Further research is warranted to confirm these results in order to develop new interventions to improve outcome from radiation treatment.

Recent advances in multidisciplinary approach for rectal cancer

Surgery is a major treatment option for rectal cancer, and total mesorectal excision has been demonstrated to be advantageous in terms of oncological outcome and thus has been the standard surgical approach. Radiotherapy before or after radical surgery is the optimal treatment to control local recurrence of advanced rectal cancer. To date, in many countries, the combination of neoadjuvant concurrent chemotherapy and radiotherapy is considered the standard therapy. A more recent interest in neoadjuvant therapy has been the use of oxaliplatin or targeted agents for neoadjuvant chemoradiotherapy. However, despite many trials of oxaliplatin and targeted agents, 5-FU-based concurrent chemoradiotherapy has remained the only standard treatment option. Postoperative adjuvant chemotherapy with neoadjuvant chemoradiotherapy or induction chemotherapy with neoadjuvant chemoradiotherapy may further improve patient survival, as some clinical studies recently indicated. In Japan, neoadjuvant therapy is not the standard treatment method, because surgery with lateral lymph node dissection is usually performed and this type of surgery may reduce recurrence rate as does radiation therapy. The phase III study to evaluate the oncological effect of the Japanese standard operation (mesorectal excision, ME) with lateral lymph node dissection in comparison with ME alone for clinical stage II and III lower rectal cancer is currently ongoing.

Multidisciplinary treatment of rectal cancer in 2014: where are we going?

In the present review we discuss the recent developments and future directions in the multimodal treatment of locally advanced rectal cancer, with respect to staging and re-staging modalities, to the current role of neoadjuvant chemo-radiation and to the conservative and more limited surgical approaches based on tumour response after neoadjuvant combined therapy. When initial tumor staging is considered a high accuracy has been reported for T pre-treatment staging, while preoperative lymph node mapping is still suboptimal. With respect to tumour re-staging, all the current available modalities still present a limited accuracy, in particular in defining a complete response. The role of short vs long-course radiotherapy regimens as well as the optimal time of surgery are still unclear and under investigation by means of ongoing randomized trials. Observational management or local excision following tumour complete response are promising alternatives to total mesorectal excision, but need further evaluation, and their use outside of a clinical trial is not recommended. The preoperative selection of patients who will benefit from neoadjuvant radiotherapy or not, as well as the proper identification of a clinical complete tumour response after combined treatment modalities,will influence the future directions in the treatment of locally advanced rectal cancer.

Could preoperative short-course radiotherapy be the treatment of choice for localized advanced rectal carcinoma?

Short-course preoperative radiotherapy (RT) is widely used in northern Europe for locally advanced resectable rectal cancer, but its role in the era of advanced imaging techniques is uncertain. Here, we reviewed articles and abstracts on SCRT published from 1974 through 2013 with the goal of identifying patients who might be best suited for short-course RT. We included relevant articles comparing surgery with or without preoperative radiation published before and after the advent of total mesorectal excision. We also analyzed two randomized trials directly comparing short-course RT with conventionally fractionated chemoradiation (the Polish Colorectal Study Group and the Trans-Tasman Radiation Oncology Group) that compared short-course RT with conventional chemoradiotherapy. We conclude from our review that short-course RT can be generally applied for operable rectal cancer and produces high rates of pelvic control with acceptable toxicity; it reduces local recurrence rates but does not increase overall survival. SCRT seems to be best used for tumors considered "low risk," i.e., those that are >5 cm from the anal margin, without circumferential margin involvement, and involvement of fewer than 4 lymph nodes. Whether sequential chemotherapy can further improve outcomes remains to be seen, as does the best time for surgery (immediately or 6-8 weeks after RT). We further recommend that selection of patients for short-course RT should be based on findings from magnetic resonance imaging or transrectal ultrasonography.