Rectal cancer patients may skip surgery with chemo and watchful waiting

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Histologically confirmed diagnosis of rectal adenocarcinoma * Eligible for curative resection of rectal adenocarcinoma * Rectal tumor location =\< 12 cm from the anal verge as determined by endoscopy or magnetic resonance imaging (MRI) (if endoscopy report is not available or deemed inadequate my treating oncologist) * Nodal involvement confined to the radiation field * Radiologically measurable or clinically evaluable disease as defined in the protocol * Eastern Cooperative Oncology Group (ECOG) performance status (PS): 0, 1 or 2 * Clinical Stage: Stage II and III. N2 disease is to be estimated as four or more lymph nodes that are \>= 10 mm. Clinical staging should be estimated based on the combination of the following assessments: physical exam by the primary surgeon including digital rectal exam (DRE), computed tomography (CT) or positron emission tomography (PET)/CT scan of the chest/abdomen/pelvis and a pelvic MRI. If a pelvic MRI is performed, it is acceptable to perform CT of the chest/abdomen, omitting CT imaging of the pelvis. PET/CT is optional. * No known contraindication to standard (fluoropyrimidine-based) pelvic chemoradiation (e.g. dihydropyrimidine dehydrogenase \[DPD\] deficiency) * Patient of child-bearing potential is willing to employ adequate contraception during treatment and after treatment, as directed by treating clinical team * Willing to provide written informed consent * Willing to return to enrolling medical site for all study assessments Exclusion Criteria: * Diagnosis of inflammatory bowel disease (IBD) * Diagnosis of MSI-H colorectal cancer at time of consent * Recurrent rectal cancer * Tumor is causing symptomatic bowel obstruction (patients who have diverting ostomy are eligible) * Any prior pelvic radiation * Other invasive malignancy undergoing active treatment. Patients receiving prior treatment that precludes standard chemoradiation or ability to receive consolidation/adjuvant chemotherapy will be excluded from survival analyses * Patients unwilling or unable to undergo pelvic MRI