Oligometastatic Disease in the Peritoneal Space with Gastrointestinal Cancer

Total abdominal colectomy to facilitate complete cytoreduction in 56 patients with mucinous appendiceal neoplasms with peritoneal metastases

BACKGROUND

Cytoreductive surgery (CRS) and perioperative intraperitoneal chemotherapy are currently the standard of care for management of appendiceal mucinous neoplasms with peritoneal metastases. The goal of the CRS is complete removal of all visible disease through the use of peritonectomy procedures and visceral resections. One of the major resections that may be required is total abdominal colectomy (TAC).

METHODS

From a database and secured files of patients having a complete CRS, all patients who had TAC were identified. The clinical and histologic variables associated with these patients were identified and assessed for their impact on overall survival.

RESULTS

The 450 complete CRS with low-grade appendiceal mucinous neoplasms had 26 TAC (5.8%) with a 16.0-year median survival. The mucinous adenocarcinoma (MACA)-Intermediate (MACA-Int) group consisted of 37 patients with 8 patients (21.6%) having TAC that resulted in a median survival of 11.5 years. The 159 complete CRS with MACA had 22 TAC (13.8%) with a median survival of 7.5 years. There was a single mortality with a class 4 adverse event in 5 patients (10.7%). With a class 4 adverse event, survival decreased significantly (p = 0.0006, hazard ratio: 6.2).

CONCLUSION

Complete CRS required TAC in 56 of 646 patients (8.7%) with appendiceal mucinous neoplasms. With TAC, median survival was 12.0 years. A class 4 adverse event markedly reduced survival.

Case Report: First in Human Online Adaptive MR Guided SBRT of Peritoneal Carcinomatosis Nodules: A New Therapeutic Approach for the Oligo-Metastatic Patient

Peritoneal carcinosis (PC) is characterized by poor prognosis. PC is currently treated as a locoregional disease and the possibility to perform very precise treatments such as stereotactic body radiation therapy (SBRT) has opened up new therapeutic perspectives. More recently, the introduction of Magnetic Resonance-guided Radiation Therapy (MRgRT) allowed online adaptation (OA) of treatment plan to optimize daily dose distribution based on patient’s anatomy. The aim of this study is the evaluation of the effectiveness of SBRT OA workflow in an oligometastatic patient affected by PC. We report the clinical case of a patient affected by PC originating from colon cancer, previously treated with chemotherapy and surgery, addressed to OA SBRT treatment on a single chemoresistant PC nodule, delivered with a 0.35 T MR Linac. Treatment was delivered using gating approach in deep inspiration breath hold condition in order to reduce intrafraction variability. Prescription dose was 35 Gy in 5 fractions. The PTV V95% of the original plan was 96.6%, while the predicted values for the following fractions were 11.9, 56.4, 0, 0, and 61%. Similarly, the small bowel V19.5 Gy of the original plan was 4.63 cc, while the predicted values for the following fractions were 3.7, 8.6, 10.7, 1.96, 3.7 cc. Thanks to the OA approach, the re-optimized PTV V95% coverage improved to 96.1, 89.0, 85.5, 94.5, and 94%; while the small bowel V19.5 Gy to 3.36; 3.28; 1.84; 2.62; 2.6 cc respectively. After the end of RT, the patient was addressed to follow-up, and the re-evaluation ¹⁸F-FDG PET-CT was performed after 10 months from irradiation showed complete response. No acute or late toxicities were recorded. MRgRT with OA approach in PC patients is technically and clinically feasible with clean toxicity result. Online adaptive SBRT for oligometastases opens up new therapeutic scenarios in the management of this category of patients.