Colorectal cancers and ovarian cancers are respectively the 2nd and 5th cause of cancer mortality in France.

Surgical resection is a crucial step in the therapeutic management of colorectal cancers. For advanced ovarian cancers, the objective of cytoreductive surgery is to obtain complete macroscopic resection with no visible residual disease. One or more digestive resections are often required to achieve this goal of complete surgery (usually a modified posterior pelvic exenteration with colorectal resection).

A ligation of the inferior mesenteric artery at its origin is classically performed in left colectomies and rectal resection for colorectal cancers. This allows the resection of the colorectal segment with a complete mesocolic lymphadenectomy until the origin of the inferior mesenteric artery and a good mobilization of the descending colon to allow its anastomosis to the underlying rectal stump. This ligation of the inferior mesenteric artery at its origin is also frequently performed in cases of modified posterior pelvic exenteration for ovarian cancer.

Recently, several studies suggest that arterial ligation of the inferior mesenteric artery could be performed below the emergence of the left colic artery. Its preservation requiring a meticulous vascular dissection would allow a better vascularization of the descending colon and of the colorectal anastomosis without affecting the carcinologic quality of the resection and the number of resected lymph-nodes. Indeed, the most feared complication during colorectal anastomosis is the anastomotic leakage whose rates are on average 15% in rectal cancer with low anastomosis and 6% in ovarian cancers.

Verifying the adequate vascularization of the descending colon before performing the colorectal anastomosis is a crucial step in reducing the risk of postoperative fistula. However, quantifying this vascularization is challenging, and several techniques can be used to assess it. The gold standard technique involves measuring arterial pressure using a catheter inserted into the marginal artery of the descending colon. Other non-invasive techniques also use Doppler studies to calculate pressure in the marginal artery or assess oxygen saturation using a sterile sensor.

Studies have shown that the use of indocyanine green in colorectal surgery, particularly to evaluate perfusion before the creation of an anastomosis, significantly reduces the rate of anastomotic leakage. Indocyanine green is a fluorescent dye that, after intravenous injection, binds to plasma proteins and allows tissue perfusion to be visualized using a fluorescence system.

The objective of this project is to show that the preservation of the left colic artery is possible and allows a better vascularization of the descending colon before colorectal anastomosis.

Inclusion Criteria:

• Male/ female aged over 18 years,
• Histologically proven left colon or rectal adenocarcinoma OR ovarian carcinoma (with potential colorectal resection),
• Scheduled surgery for left colic or rectal carcinoma// Scheduled surgery for ovarian carcinoma with potential colorectal resection,
• Surgical indication of colo-rectal resection validated in RCP and confirmed during the operative exploration (ovarian cancer,
• WHO Status < 3
• Patient who has given informed, written and express consent,
• Patient (s) affiliated to a French social security.

Exclusion Criteria:

• Contraindication to indocyanine green: thyroid adenoma, hyperthyroidism, hypersensitivity or allergy to one of the components, severe renal failure (GFR <30 ml/min/1.73m2),
• Patient with a history of abdominal vascular surgery
• Patient (e) not having left colic artery on vascular mapping of preoperative abdominal-pelvic scanners,
• Patient whose regular follow-up is not possible for psychological, family, social or geographical reasons,
• Patient (s) under guardianship, curatorship or safeguard of justice,
• Pregnant and/or breastfeeding patient,

All data will be available after publication of the results in peer-reviewed revues, and in national and international meetings. It includes all de-identified participants' data, the study protocol, the statistical analysis plan and the clinical study report. The corresponding author will provide data and datasets generated and/or analyzed during the study upon reasonable request.

Access to study data upon written detailed request sent to ICM, from 6 months until 5 years after publication of summary data.

The data shared will be limit to that required for independent mandated verification of the published results, the applicant will need authorization from ICM for personal access, and data will only be transferred after signing of a data access agreement.