PET/MRI as a Predictor of Response to Pre-op Chemoradiation in Resectable Rectal Cancer: a Pilot Study

Inclusion Criteria:

* Low-lying, low- to moderate-risk pathologically-confirmed rectal cancer (stage uT3n) or uT1-3N+
* Negative workup for distant disease
* \> 18 years of age
* Pre-treatment workup completed including:
* history and physical
* CT or MRI of the abdomen and pelvis
* endoscopic tumor evaluation (biopsy, blood work to assess CEA and hematopoietic, renal and liver function)
* if female of child-bearing age, negative pregnancy test
* Recommendation to undergo preoperative concurrent chemoradiation, as determined by the treating physician
* Informed consent reviewed and signed

Exclusion Criteria:

* Not deemed a candidate for preoperative chemoradiation for medical reasons, such as uncontrolled infection (including HIV), uncontrolled diabetes mellitus or cardiac disease
* Hemoglobin ≤ 10.0 g/dL (transfusion allowed to achieve or maintain levels)
* ANC ≤ 1,500/cubic mm³
* Platelet count ≤ 100,000/mm³
* ALT and AST ≥ 2.5 times upper level of normal (ULN)
* Alkaline phosphatase ≥ 2.5 times ULN
* Total bilirubin ≥ 1.5 times ULN
* Creatinine clearance \< 50 mL/min
* Creatinine ≥ 1.5 times ULN
* Not deemed a candidate for concurrent preoperative chemoradiation for social reasons, such as psychiatric illness
* Not deemed a surgical candidate
* Currently active second malignancy, except non-melanoma skin cancer, non-invasive bladder cancer, low risk adenocarcinoma of the prostate and carcinoma in situ of the cervix
* Previous pelvic radiation therapy
* History of severe reaction to gadolinium
* Inability to tolerate MRI (e.g., inability to lie flat for \> 1 hour)
* Presence of a pacemaker, intracranial aneurysm clip, bladder stimulator, cochlear implant or metal near eyes
* Body Mass Index (BMI) \> 35
* Pregnant or lactating female