Randomized clinical trials in rectal and anal cancers

Neoadjuvant chemo-radiotherapy for cT3N0 rectal cancer: any benefit over upfront surgery? A propensity score-matched study

PURPOSE

Benefits of neoadjuvant chemo-radiotherapy (CRT) are well known for locally advanced and/or node-positive rectal cancer, but the best timing for CRT has been less explored for cT3N0 patients. The aim of the present study was to compare the 5-year disease-free survival (DFS) probability between neoadjuvant CRT and upfront surgery in patients affected by cT3N0 rectal cancer.

METHODS

A retrospective review of 105 patients affected by cT3N0 rectal cancer, staged by pelvic magnetic resonance imaging and treated at the National Cancer Institute of Milan between 2011 and 2017, was performed: 42 (40.0%) were treated by neoadjuvant CRT and 63 (60.0%) by upfront surgery. Propensity score matching was performed to avoid selection bias, and Cox multivariate regression was used to analyze outcomes.

RESULTS

The 5-year DFS probability was 87.5% in neoadjuvant CRT patients vs. 90.0% in upfront surgery cases (Log-rank p = 0.76). The 5-year loco-regional recurrence-free survival probability was respectively 96.8% vs. 96.3% (Log-rank p = 0.954). On multivariate analysis, neoadjuvant CRT had no impact on DFS when compared to upfront surgery (adjusted HR 0.71, 95%CI 0.18-2.70, p = 0.613), but 61.9% of upfront surgery cases were treated by adjuvant chemo-radiation (adjusted HR 0.41, 95%CI 0.11-1.57, p = 0.196). The only independent predictor of improved DFS was age at diagnosis (adjusted HR 0.95, p = 0.017).

CONCLUSION

CRT should be considered for cT3N0 patients, but its timing (neoadjuvant vs. adjuvant) seems not to affect the disease-free survival in the present cohort of patients.

Randomized Clinical Trials in Colon and Rectal Cancer

Surgery remains the mainstay of treatment for colon and rectal cancers. Colon cancer outcomes have improved with laparoscopic techniques, enhanced recovery pathways, and adjuvant chemotherapy. Adjuvant 5-fluorouracil with or without oxaliplatin in stage III and possibly high-risk stage II colon cancer is associated with improved survival. Multimodality management of rectal cancer continues to evolve; total mesorectal excision is the cornerstone. Oncologic results do not support the use of laparoscopic resection in rectal cancer. Preoperative short- or long-course radiation for stage II or III rectal cancer is the standard of care. Long course chemoradiation is recommended for bulky tumors.

Surgery for Locally Advanced T4 Rectal Cancer: Strategies and Techniques

Locally advanced T4 rectal cancer represents a complex clinical condition that requires a well thought-out treatment plan and expertise from multiple specialists. Paramount in the management of patients with locally advanced rectal cancer are accurate preoperative staging, appropriate application of neoadjuvant and adjuvant treatments, and, above all, the provision of high-quality, complete surgical resection in potentially curable cases. Despite the advanced nature of this disease, extended and multivisceral resections with clear margins have been shown to result in good oncological outcomes and offer patients a real chance of cure. In this article, we describe the assessment, classification, and multimodality treatment of primary locally advanced T4 rectal cancer, with a focus on surgical planning, approaches, and outcomes.

Surgical oncology issues in locally advanced rectal cancer

The management of locally advanced (T3/4) rectal cancer is evolving. Randomized trials have shaped the current adjuvant treatment options, but yet there remain many unanswered questions. These include how best to define which patients to treat and choosing between short-course radiotherapy and long-course chemoradiotherapy. With respect to surgery, the optimal timing, the surgical approach in abdominoperineal resections and the role of laparoscopic surgery remain active areas of research. The possibility of avoiding surgery in selected patients is also a topic of great interest. A multidisciplinary team approach in managing rectal cancer patients is popular where possible and recommended in some guidelines.

Relationship of EMAST and microsatellite instability among patients with rectal cancer

BACKGROUND

Elevated microsatellite instability at selected tetranucleotide repeats (EMAST) is a genetic signature identified in 60% of sporadic colon cancers and may be linked with heterogeneous expression of the DNA mismatch repair (MMR) protein hMSH3. Unlike microsatellite instability-high (MSI-H) in which hypermethylation of hMLH1 occurs followed by multiple susceptible gene mutations, EMAST may be associated with inflammation and subsequent relaxation of MMR function with the biological consequences not known. We evaluated the prevalence of EMAST and MSI in a population-based cohort of rectal cancers, as EMAST has not been previously determined in rectal cancers.

METHODS

We analyzed 147 sporadic cases of rectal cancer using five tetranucleotide microsatellite markers and National-Cancer-Institute-recommended MSI (mononucleotide and dinucleotide) markers. EMAST and MSI determinations were made on analysis of DNA sequences of the polymerase chain reaction products and determined positive if at least two loci were found to have frame-shifted repeats upon comparison between normal and cancer samples from the same patient. We correlated EMAST data with race, gender, and tumor stage and examined the samples for lymphocyte infiltration.

RESULTS

Among this cohort of patients with rectal cancer (mean age 62.2 ± 10.3 years, 36% female, 24% African American), 3/147 (2%) showed MSI (three males, two African American) and 49/147 (33%) demonstrated EMAST. Rectal tumors from African Americans were more likely to show EMAST than Caucasians (18/37, 49% vs. 27/104, 26%, p = 0.014) and were associated with advanced stage (18/29, 62% EMAST vs. 18/53, 37%, non-EMAST p = 0.02). There was no association between EMAST and gender. EMAST was more prevalent in rectal tumors that showed peri-tumoral infiltration compared to those without (30/49, 60% EMAST vs. 24/98, 25% non-EMAST, p = 0.0001).

CONCLUSIONS

EMAST in rectal cancer is common and MSI is rare. EMAST is associated with African-American race and may be more commonly seen with metastatic disease. The etiology and consequences of EMAST are under investigation, but its association with immune cell infiltration suggests that inflammation may play a role for its development.