Cytoreductive surgery followed by systemic chemotherapy is most appropriate in this patient with abdominal carcinomatosis due to cancer of unknown primary site (CUP). When evaluating a patient with CUP, it is important to identify whether the CUP is of a favorable or unfavorable prognostic subgroup to help guide management. Women with CUP presenting as abdominal carcinomatosis and ascites are classified as a favorable prognostic subgroup and should be assumed to have ovarian cancer until proved otherwise. Treatment is the same as for primary ovarian cancer and includes cytoreductive surgery (tumor debulking along with total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, selective lymphadenectomy, and appendectomy, as well as administration of a platinum/taxane-containing chemotherapy regimen).

Ovarian cancer is unique in that its spread is mostly confined to the peritoneal cavity. The use of adjuvant intraperitoneal chemotherapy plus intravenous chemotherapy offers a survival advantage to intravenous chemotherapy alone. However, this survival advantage is associated with substantially increased toxicity. Combined intraperitoneal and intravenous chemotherapy without cytoreduction surgery is not adequate therapy for patients with CUP presenting as ovarian cancer–like disease.

Radiation therapy and concurrent chemotherapy are recommended for patients with stage IB through stage IV cervical cancer, as large randomized clinical trials have confirmed a survival advantage with this combined approach. This approach is not effective for patients with peritoneal carcinomatosis and ascites.

Systemic chemotherapy without cytoreductive surgery would be inadequate as the initial treatment of a patient with an ovarian cancer–like presentation.

Because this patient has a significant chance of meaningful benefit from treatment and has no comorbidities, providing only supportive care would be inappropriate.