The Nonoperative Management of Rectal Cancer

At the virtual 2020 Great Debates & Updates in Gastrointestinal Malignancies meeting, Julio Garcia-Aguilar, MD, PhD, Memorial Sloan Kettering Cancer Center, New York, provided insight on the nonoperative management of rectal cancer.

Dr. Garcia-Aguilar began by discussing how some rectal cancers appear to be eradicated by neoadjuvant therapy, but the question remains if patients with a complete response to neoadjuvant therapy benefit from total mesorectal excision (TME).

To answer this, Dr. Garcia-Aguilar shared the early results of a large, international watch and wait (W&W) approach study done by Dr. Habr-Gama et al.

“She found that patients with a complete response to neoadjuvant therapy who were treated with a nonoperative approach had equivalent outcomes compared to patients who had surgery and were found to have a pathological complete response.”

Although the W&W approach has shown operative treatment is not always necessary for rectal cancer, several questions raised during the presentation that need to be considered included: how to predict and maximize response and how often to survey patients with this approach.

Total neoadjuvant therapy (TNT) and delayed assessment of tumor response have shown to be effective in enhancing response. In a study done by Dr. Garcia-Aguilar and colleagues, the use of chemoradiation and TNT followed by consolidation chemotherapy yielded an increased response rate amongst patients.

Dr. Garcia-Aguilar explained the identification of true responses is a challenge that needs to be refined, as clinical and radiological criteria underestimate the response to CRT in rectal cancer.

The three current modalities for rectal cancer are a digital rectal exam (DRE), endoscopy, and imaging (MRI), but DRE underestimates the response in 78% of patients: 66% of patients with pCR had residual mucosal abnormalities, and even when all 3 modalities indicated residual tumor, there was still a 15% chance the patient had pCR and there was no tumor left.

Dr. Garcia-Aguilar and researchers at Memorial Sloan Kettering developed a rectal cancer regression schema to combat this dilemma.

“We combined endoscopy, digital rectal exam, and MRI sequences to stratify responses in three categories: those that had a clearly complete response - that they can be a candidate for watch and wait; those without response, they will need to have immediate surgery; and then a group in the middle of near complete responders, patients that at the time of evaluation we couldn't tell for sure whether the tumor was gone or not."

They found the rectal regression schema to provide the best accuracy for clinical complete response (cCR), intermediate for incomplete clinical response (iCR), and worse for near complete response (nCR). Further validation is needed.

Tumor regrowth, which is often slow and indolent, can be identified early if the patient complies with a strict surveillance protocol. Dr. Garcia-Aguilar highlighted that if regrowth does occur, most of the time it is salvageable by TME if caught early.  

Regarding distant metastasis, recent data suggests the rate is similar between TME and W&W treatment approaches, at 7% and 5-8%, respectively.

 “I think watch and wait is acceptable to most rectal cancer patients and it’s already demanded by some, I would say many, and I think it should be part of the treatment discussion today,” concluded Dr. Garcia-Aguilar, stressing that close surveillance and longer follow-up is essential for nonoperative management of rectal cancer.

“I think for a successful watch and wait, it requires well informed patients, who are willing to undergo a very intensive surveillance protocol.”