Responses to Therapy for Ovarian and Other Women’s Cancers May Have to be Assessed Beyond Imaging and Blood Test Modalities

Two methods to evaluate the response to therapy may not be accurate assessments in women with ovarian cancer, fallopian tube cancer or primary peritoneal carcinoma who were treated with chemotherapy before surgery, according to a study published in Lancet Oncology.

“This large evaluation in a clearly defined patient population demonstrates the difficulties in using current well-defined unidimensional radiological and biochemical response surrogates to assess the therapeutic impact of neoadjuvant chemotherapy in advanced high-grade ovarian cancer,” the study authors wrote. “Both response criteria imperfectly predict the ability to achieve complete or optimal cytoreduction at interval surgery — a more robust surrogate for survival, or indeed progression-free survival.”

The two criteria assessed in this study were Response Evaluation Criteria in Solid Tumors (RECIST) and cancer antigen 125 (CA125). RECIST requires CT scans, X-rays or MRI scans to measure at least one tumor, whereas CA125 is a marker that can be measured in blood, with reductions in CA125 indicating treatment response.

To analyze these two criteria, researchers utilized them in 779 women with fallopian tube, ovary or primary peritoneum cancer who underwent chemotherapy with carboplatin-paclitaxel followed by delayed primary surgery. In particular, patients were randomly assigned the following chemotherapy regimens, with a maximum number of six chemotherapy cycles allowed.

• Carboplatin (capped at 900 mg) and paclitaxel (175 mg/m2 by body surface area, capped at 350 mg) on the first day of every 21-day cycle (257 patients; median age, 65 years);
• Carboplatin (capped at 900 mg) on the first day and paclitaxel (80 mg/m2 by body surface area, capped at 160 mg) on days one, eight and 15 of every 21-day cycle (263 women; median age, 62 years); or
• Carboplatin (capped at 300 mg) and paclitaxel (80 mg/m2 by body surface area, capped at 160 mg) on days one, eight and 15 of every 21-day cycle (259 women; median age, 64 years).

One of the outcomes of interest in this study was progression-free survival, defined as the time between radiological tumor assessment performed during presurgical planning and either disease progression or death, whichever occurred first. Follow-up was performed for a median of 29.5 months.

Of the women in the study, 564 had available data to be assessed by RECIST criteria, whereas 727 had available data to assess CA125 criteria. Complete or partial response to therapy was observed in 62% of women according to RECIST criteria compared with 84% of women who had a CA125 response.

Patients with complete or partial response to therapy according to RECIST criteria had a median progression-free survival of 14.4 months compared with 13.3 months for those who had stable disease using the same criteria. Median progression-free survival for women with a CA125 response was 13.8 months versus 9.7 months for those without a response.

Complete cytoreduction, or the absence of any visible disease, was achieved by 56% of patients with a complete or partial response to therapy according to RECIST criteria compared with 42% of those with stable disease. This was also achieved by 50% of patients with a CA125 response versus 30% of those without a response.

“We recommend … that RECIST and CA125 assessments should not be considered as standalone measures to stratify patients who are likely to benefit from (delayed primary surgery), but instead used in conjunction with the patient’s clinical capacity (eg, performance status and comorbidities) to undergo cytoreductive surgery,” the study authors wrote.

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