Low rectal cancer treatment strategies: a cohort study assessing watch and wait

The ultimate local failure rate after the watch-and-wait strategy for rectal cancer: a systematic review of literature and meta-analysis

BACKGROUND

We hypothesise that a high rate of tumour regrowth after the watch-and-wait (w&w) strategy may lead, despite salvage surgery, to a significant impairment of ultimate local control compared with immediate surgery.

MATERIALS AND METHODS

To test this hypothesis, we conducted meta-analyses of studies on the w&w strategy (both opportunistic and planned) with an ultimate local failure rate as an endpoint in three patient groups: (1) in all starting radio(chemo)therapy as potential w&w candidates, (2) in a subgroup starting w&w, and (3) in a subgroup with regrowth.

RESULTS

We identified eight studies for evaluation of local failure in group 1 (N = 837) and 36 studies in group 2 (N = 1914) and in group 3 (N = 439). The meta-analysis revealed an ultimate local failure rate of 8.0% (95% CI 4.8%-12.1%) in group 1 and 5.4% (95% CI 3.9%-7.1) in group 2. These rates are similar to those reported in the literature following preoperative chemoradiation and surgery. However, in the most unfavourable group 3 (with regrowth), the rate of ultimate local failure was 24.1% (95% CI 17.9%-30.9%), with the most common causes being patients' refusal of salvage total mesorectal excision (TME) (9.1%), recurrence after salvage TME (7.8%), distant metastases (4.1%), frailty (2.4%), and pelvic tumour unresectability (1.7%).

CONCLUSION

Nearly 25% of patients with regrowth (unfavourable subgroup) experienced ultimate local failure, primarily due to refusing salvage TME. The risk of ultimate local failure in patients initiating radio(chemo)therapy as potential w&w candidates, or in patients starting w&w, appears comparable to that reported after preoperative chemoradiation and surgery. However, this comparison may be biased, because w&w studies included more early tumours compared with surgical studies.

Outcomes after the watch-and-wait strategy and local excision treatment for rectal cancer: a meta-analysis

BACKGROUND

The watch-and-wait (W&W) strategy and local excision (LE) have been used in patients with clinical complete response (cCR) for rectal cancer, but the comparative outcomes of the two strategies are controversial. We compared the efficacy of the W&W strategy with LE for rectal cancer patients after neoadjuvant chemoradiotherapy (nCRT) or total neoadjuvant therapy (TNT).

RESEARCH DESIGN AND METHODS

Several domestic and foreign databases were searched for the relevant literature on comparative trials of the W&W strategy and LE surgery for rectal cancer after neoadjuvant therapy with the following outcomes; differences in local recurrence (LR), distant metastasis (DM/DM+LR), 3-year disease-free survival (DFS), 3-year local recurrence-free survival (LRFS) and 3-year overall survival (OS).

RESULTS

Nine articles, were analyzed. Overall, 442 patients were included, with 267 and 175 patients in the W&W and LE groups, respectively. Meta-analysis results showed no significant differences the between W&W and LE groups with respect to LR, DM/DM+LR, 3-year DFS, 3-year LRFS, and 3-year OS. This study has been registered in PROSPERO (registration number: CRD42022331208).

CONCLUSION

The W&W strategy may be preferred for some rectal cancer patients who select LE and reach cCR or near cCR after nCRT or TNT.

Endoscopy-Based Deep Convolutional Neural Network Predicts Response to Neoadjuvant Treatment for Locally Advanced Rectal Cancer

Background and Aims: Although the wait and watch (W&W) strategy is a treatment choice for locally advanced rectal cancer (LARC) patients who achieve clinical complete response (cCR) after neoadjuvant therapy (NT), the issue on consistency between cCR and pathological CR (pCR) remains unsettled. Herein, we aimed to develop a deep convolutional neural network (DCNN) model using endoscopic images of LARC patients after NT to distinguish tumor regression grade (TRG) 0 from non-TRG0, thus providing strength in identifying surgery candidates. Methods: A total of 1000 LARC patients (6,939 endoscopic images) who underwent radical surgery after NT from April 2013 to April 2021 at the Sixth Affiliated Hospital, Sun Yat-sen University were retrospectively included in our study. Patients were divided into three cohorts in chronological order: the training set for constructing the model, the validation set, and the independent test set for validating its predictive capability. Besides, we compared the model's performance with that of three endoscopists on a class-balanced, randomly selected subset of 20 patients' LARC images (10 TRG0 patients with 70 images and 10 non-TRG0 patients with 72 images). The measures used to evaluate the efficacy for identifying TRG0 included overall accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUROC). Results: There were 219 (21.9%) cases of TRG0 in the included patients. The constructed DCNN model in the training set obtained an excellent performance with good accuracy of 94.21%, specificity of 94.39%, NPV of 98.11%, and AUROC of 0.94. The validation set showed accuracy, specificity, NPV, and AUROC of 92.13%, 93.04%, 96.69%, and 0.95, respectively; the corresponding values in the independent set were 87.14%, 92.98%, 91.37%, and 0.77, respectively. In the reader study, the model outperformed the three experienced endoscopists with an AUROC of 0.85. Conclusions: The proposed DCNN model achieved high specificity and NPV in detecting TRG0 LARC tumors after NT, with a better performance than experienced endoscopists. As a supplement to radiological images, this model may serve as a useful tool for identifying surgery candidates in LARC patients after NT.

Predicting pathologic complete response in locally advanced rectal cancer patients after neoadjuvant therapy: a machine learning model using XGBoost

PURPOSE

Watch and wait strategy is a safe and effective alternative to surgery in patients with locally advanced rectal cancer (LARC) who have achieved pathological complete response (pCR) after neoadjuvant therapy (NAT); present restaging methods do not meet clinical needs. This study aimed to construct a machine learning (ML) model to predict pCR preoperatively.

METHODS

LARC patients who received NAT were included to generate an extreme gradient boosting-based ML model to predict pCR. The group was divided into a training set and a tuning set at a 7:3 ratio. The SHapley Additive exPlanations value was used to quantify feature importance. The ML model was compared with a nomogram model developed using independent risk factors identified by conventional multivariate logistic regression analysis.

RESULTS

Compared with the nomogram model, our ML model improved the area under the receiver operating characteristics from 0.72 to 0.95, sensitivity from 43 to 82.2%, and specificity from 87.1 to 91.6% in the training set, the same trend applied to the tuning set. Neoadjuvant radiotherapy, preoperative carbohydrate antigen 125 (CA125), CA199, carcinoembryonic antigen level, and depth of tumor invasion were significant in predicting pCR in both models.

CONCLUSION

Our ML model is a potential alternative to the existing assessment tools to conduct triage treatment for patients and provides reference for clinicians in tailoring individual treatment: the watch and wait strategy is used to avoid surgical trauma in pCR patients, and non-pCR patients receive surgical treatment to avoid missing the optimal operation time window.

The growing trend for no primary surgery in colorectal cancer

AIM

In colorectal cancer (CRC), surgery of the primary site is commonly curative. Our aim was to determine estimates of 'no surgery' for primary CRC while identifying common reasons for no surgery.

METHOD

We identified all patients with a diagnosis of colorectal adenocarcinoma from the National Cancer Database between January 2004 and December 2016. Then, we identified patients who did not undergo surgery on the primary tumour and their demographic, tumour and institutional characteristics. Kaplan-Meier and logistic regression analyses were used to evaluate specific factors associated with overall survival as related to no surgery and recommendations against operative management.

RESULTS

A total of 1,208,878 patients with CRC were identified, 14.5% of whom had no surgery of the primary cancer. No surgery was more common in rectal cancer than in colon cancer. Despite a steady incidence of CRC diagnoses, the likelihood of no surgery grew by 170% over the study period. Metastatic disease was noted in 53.7% of the no surgery cohort. Nine per cent of the no surgery patient cohort received a recommendation against surgery despite the absence of metastatic disease, 7.5% refused surgery and only 2% underwent palliative surgery. On multivariable analysis, patients who were not recommended to have surgery were more likely to be older, uninsured, comorbid and receive care at a single hospital. The no surgery patients had significantly lower overall survival.

CONCLUSION

A substantial proportion of patients with CRC do not have surgery. Interventions aimed at expanding access and promoting second opinions at other cancer hospitals might reduce the growing rate of no surgery in CRC.

Watch-and-wait strategy in rectal cancer: Is there a tumour size limit? Results from two pooled prospective studies

BACKGROUND

Frequency and predictive factors for a clinical complete response (cCR) in unselected patients are unclear.

MATERIAL AND METHODS

Two prospective observational studies were designed and pooled to explore predictive factors for cCR. Both studies evaluated the watch-and-wait strategy in consecutive patients; the first single-institutional study in elderly with a small tumour, the second multi-institutional study in all the patients receiving standard of care preoperative radiotherapy.

RESULTS

Four hundred and ninety patients were analysed. Short-course radiotherapy alone, or with consolidation chemotherapy or chemoradiation was given to 40.6%, 40.2% and 19.2% of the patients, respectively. The median interval from the radiation start to the first tumour response assessment was 10.2 weeks for short-course radiation and 13.2 weeks for chemoradiation. Seventy-three patients had cCR and 71 underwent w&w with the median follow-up of 24 months. The regrowth rate was 26.8%. cCR rate was 39.0% for low-risk cancer (cT1-2N0), 16.8% for intermediate-risk (cT3 with unthreatened mesorectal fascia [MRF-] or cT2N+) and 5.4% for high-risk (cT4 or MRF+). In the multivariable analysis, tumour volume (or tumour length and circumferential extent) and cN status were significant predictors for cCR. In circular cancers or with a length ≥7 cm (n = 184), cCR rate was only 2.7%, sustained cCR 1.6% and the sensitivity of cCR diagnosis 23.1%. None of 27 patients with a tumour larger than 120 cm³ achieved cCR.

CONCLUSIONS

Considering watch-and-wait strategy is questionable in patients with circular tumours or with tumour length ≥7 cm.