Regional lymph node status after neoadjuvant chemoradiation of rectal cancer producing a complete or near complete rectal wall response

Predictors of Nodal Disease in Rectal Cancer Patients with Complete Mucosal Response to Neoadjuvant Therapy

BACKGROUND

Some patients with locally advanced rectal cancer (LARC) achieve complete mucosal response following neoadjuvant therapy (NAT) and may be candidates for watch and wait strategy. This study aimed to identify predictors of nodal disease in patients with LARC who had a complete mucosal response to NAT.

METHODS

This case-control study included patients with LARC who were treated with NAT in the National Cancer Database between 2004 and 2019. Patients with complete mucosal response, defined as pathologic T0, were identified and classified according to the status of the pathologic N stage into complete response (pT0, pN0) and complete mucosal response with positive nodal disease (pT0, pN +). The two groups were compared regarding baseline demographics and tumor characteristics to determine the predictors of nodal disease after NAT.

RESULTS

A total of 5529 patients (59.7% male) with a mean age of 59.6 ± 12.2 years had a complete mucosal response following NAT. Nodal disease was detected in 443 (8%) patients with a complete mucosal response. Independent predictors of nodal disease were clinical N + stage (OR: 1.87, p < 0.001), mucinous histology (OR: 3.8, p = 0.003), and lymphovascular invasion (OR = 4.01, p < 0.001). The clinical T stage was inversely related to the risk of nodal disease.

CONCLUSIONS

Despite having a complete mucosal response following NAT, 8% of patients had nodal disease. Clinical evidence of nodal involvement on preoperative assessment, mucinous tumor histology, and lymphovascular invasion predicted nodal disease after NAT. These findings should be considered when making a decision on watch and wait strategy in patients with clinical complete response.

The prognostic impact of neoadjuvant chemoradiotherapy on lymph node sampling in patients with locally advanced rectal cancer

According to the American Joint Committee on Cancer, at least 12 lymph nodes are required to accurately stage locally advanced rectal cancer (LARC). Neoadjuvant chemoradiation therapy (NACRT) reduces the number of lymph nodes retrieved during surgery. In this study, we evaluated the effect of NACRT on lymph node retrieval and prognosis in patients with LARC. We performed an observational study of 142 patients with LARC. Although our analysis was retrospective, data were collected prospectively. Half the patients were treated with NACRT and total mesorectal excision (TME) and the other half underwent TME only. The number of lymph nodes retrieved and the number of metastatic lymph nodes were significantly reduced in the NACRT group (P > 0.001). In the univariate and multivariate analyses, only NACRT and patient age were significantly associated with reduced lymph node retrieval. The number of metastatic lymph nodes and the lymph node ratio (LNR) both had a significant effect on prognosis when the patient population was examined as a whole (P = 0.003 and P = 0.001, respectively). However, the LNR was the only significant, independent prognostic factor in both treatment groups (P = 0.007 for the NACRT group; P = 0.04 for the no-NACRT group). NACRT improves patient prognosis only when the number of metastatic lymph nodes is reduced. The number of metastatic lymph nodes and the LNR are important prognostic factors. Lymph node retrieval remains an indispensable tool for staging and prognostic assessment of patients with rectal carcinoma treated with NACRT.

Local excision following chemoradiotherapy in T2-T3 rectal cancer: current status and critical appraisal

Local excision following chemoradiotherapy in rectal cancer is an organ-preserving procedure which aims at reducing morbidity and functional disorders associated with total mesorectal excision (TME) in selected patients. Although TME after chemoradiotherapy remains the gold standard for locally advanced mid and low rectal cancer, in the last years multicenter research trials have offered encouraging oncologic results which have allowed to preserve the rectum in patients with a pathologic complete response after chemoradiotherapy. A review of the available literature on this topic was conducted to define the state of the art of this conservative approach and to focus on the most controversial aspects concerning local excision performed after chemoradiotherapy, in particular tumor scatter and lymph node status, completion and salvage surgery, morbidity and quality of life. The analysis of these topics should be considered, in trial setting or in current practice, for their clinical implications. Oncologic outcomes of recent trials are encouraging for part of the patients presenting T2 rectal cancer; however, TME still remains the standard treatment in clinical practice. In such cases, local excision should include a surgical safety margin of at least 1 cm from the resection margin to achieve a true negative margin from residual tumor cells. The selection of the patients should be carefully performed and their consensus extremely detailed because TME is necessary in about 30% of cases. Failing that, morbidity and quality of life are negatively affected. However, about half of these patients refuse radical surgery (45%), thus undergoing only palliative care.

The risk of nodal disease in patients with pathological complete responses after neoadjuvant chemoradiation for rectal cancer: a systematic review, meta-analysis, and meta-regression

BACKGROUND

This systematic review and meta-analysis seek to evaluate the prevalence of nodal disease in rectal cancer patients with pathological complete responses (pCR) after neoadjuvant chemoradiotherapy (ypT0N+).

METHODS

This study conformed to the PRISMA guidelines. A search was performed on major databases to identify relevant articles. Meta-analyses of pooled proportions were performed on rectal cancer with pCR and ypT0N+. Meta-regression was undertaken to identify sources of heterogeneity, and the Newcastle-Ottawa Scale (NOS) was employed to assess the risk of bias.

RESULTS

A total of 18 studies were included, totaling 7568 patients. The overall risk of bias was low, since all studies scored 6 and above out of 9 on the NOS. Preoperatively, the pooled proportions of patients with T3/T4 tumors and clinically positive nodal disease were 84.08% (95% CI 74.19 to 91.99%) and 52.14% (95% CI 35.02 to 69.00%) respectively. The prevalence of pCR in the whole pool was 18.52% (95% CI 13.31 to 24.35%; I² = 93.85%; P = 0.00), and meta-regression showed a significantly negative relationship with patient age (β = - 0.03, 95% CI - 0.03 to - 0.02; P = 0.00). The pooled prevalence of ypT0N+ was 4.61% (95% CI 2.41 to 7.28%; I² = 52.27%; P = 0.01), and meta-regression demonstrated a significantly positive relationship with male gender (β = 1.06, 95% CI 1.00 to 1.12; P = 0.04).

CONCLUSION

There is a small risk of ypN+ in patients with pCR after neoadjuvant CRT and surgery for rectal cancer. However, further research is warranted to establish these findings and to identify predictive factors for this specific group of patients.

Nodal Disease in Rectal Cancer Patients With Complete Tumor Response After Neoadjuvant Chemoradiation: Danger Below Calm Waters

BACKGROUND

A subset of patients with rectal cancer who undergo neoadjuvant chemoradiation therapy will develop a complete pathologic tumor response. Complete nodal response is not universal in these patients and is difficult to assess clinically. Quantifying the risk of nodal disease would allow for targeted therapy with either radical resection or "watchful waiting."

OBJECTIVE

This study aimed to identify risk factors for residual nodal disease in ypT0 rectal adenocarcinoma.

DESIGN

This is a retrospective case control study.

SETTINGS

The National Cancer Database 2006 to 2014 was used to identify patients for this study.

PATIENTS

Patients with stage II/III rectal adenocarcinoma who completed chemoradiation therapy followed by resection and who had ypT0 tumors were included. Patients with metastatic disease and <2 lymph nodes evaluated were excluded. Patients were divided into 2 groups: node positive and node negative.

MAIN OUTCOME MEASURES

The main outcome was nodal disease. The secondary outcome was overall survival.

RESULTS

A total of 42,257 patients with stage II/III rectal cancer underwent chemoradiation therapy and radical resection; 4170 (9.9%) patients had ypT0 tumors and 395 (9.5%) were node positive. Of patients with clinically node-negative disease (ie, pretreatment imaging), 6.2% were node positive after chemoradiation therapy and resection. In multivariable analysis, factors predictive of nodal disease included increasing (pretreatment) clinical N-stage, high tumor grade (3/4), perineural invasion, and lymphovascular invasion. Higher clinical T-stage was inversely associated with residual nodal disease. Overall 5-year survival was significantly different between patients with ypN0, ypN1, and ypN2 disease (87.4%, 82.2%, and 62.5%, p = 0.002).

LIMITATIONS

This study was limited by the lack of clinical detail in the database and the inability to assess recurrence.

CONCLUSIONS

Ten percent of patients with ypT0 tumors had positive nodes after chemoradiation therapy and resection. Factors associated with residual nodal disease included clinical nodal disease at diagnosis and poor histologic features. Patients with any of these features should consider radical resection regardless of tumor response. Others could be suitable for "watchful waiting" strategies. See Video Abstract at http://links.lww.com/DCR/A458.

NEOADJUVANT THERAPY AND SURGERY FOR RECTAL CANCER. Comparative study between partial and complete pathological response

BACKGROUND

The approach of locally advanced extra-peritoneal rectal adenocarcinoma implies a treatment with neoadjuvant chemoradiotherapy associated with total mesorectal excision surgery. However, the tumors respond variably to this neoadjuvant therapy, and the mechanisms for response are not completely understood.

OBJECTIVE

Evaluate the variables related to the complete tumor response and the outcomes of patients who underwent surgery, comparing those with partial tumor regression and those with total remission of rectal lesion, at the pathological examination.

METHODS

Retrospective analysis of medical records of 212 patients operated between 2000 and 2010, in which 182 (85.9%) obtained partial remission at neoadjuvant therapy (Group 1) and 30 (14.1%), total remission (Group 2).

RESULTS

No difference was found between the groups in relation to gender, ethnicity, age, tumor distance from the anal verge, occurrence of metastases and synchronous lesions on preoperative staging, dose of radiotherapy and performed surgery. In Group 2, was verified high rate of complete remission when the time to surgery after neoadjuvant therapy was equal or less than 8 weeks (P=0.027), and a tendency of lower levels of pretreatment carcinoembryonic antigen (P=0.067). In pathological analysis, the Group 1 presented in relation to Group 2, more affected lymph nodes (average 1.9 and 0.5 respectively; P=0.003), more angiolymphatic (19.2% and 3.3%; P=0.032) and perineural involvement (15.4% and 0%; P=0.017) and greater number of lymph nodes examined (16.3 and 13.6; P=0.023). In the late follow-up, Group 1 also had lower overall survival than Group 2 (94.1 months and 136.4 months respectively; P=0.02) and disease-free survival (85.5 months and 134.6 months; P=0.004). There was no statistical difference between Group 2 and Group 1 in local recurrence (15% and 3.4%, respectively) and distant metastasis (28% and 13.8%, respectively).

CONCLUSION

In this study, the only factor associated with complete remission of rectal adenocarcinoma was the time between neoadjuvant therapy and surgery. This group of patients had less affected lymph nodes, less angiolymphatic and perineural involvement, a longer overall and disease-free survival, but no significant statistical difference was observed in local recurrence and distant metastasis. Although the complete pathologic remission was associated with better prognosis, this not implied in the cure of the disease for all patients.