Study Highlights Differences in Cytoreduction's Impact on Survival Among Ovarian Cancer Subtypes

Compared with other histology types, the association of residual tumor volume at primary cytoreduction with survival was less robust in patients with low-grade serous ovarian carcinoma (LGSOC), according to a study published in JAMA Network Open.¹

The researchers explained surgery to perform maximal tumor cytoreduction is the typical initial therapy for patients with advanced-stage ovarian cancer.² At surgery completion, the extent of residual disease is highly prognostic, with lower-volume residual disease associated with improved survival.³

Most past studies that examined the association between cytoreductive efforts and survival included high-grade and serous ovarian tumors, the most common histologic subtypes of ovarian cancer.² However, the impact of cytoreductive status on prognosis in patients with less common histologic types has been understudied.

Because of the clinical and biological differences across histologic subtypes, the researchers conducted a study to examine the association between primary cytoreduction status and survival for those with less common, advanced-stage epithelial ovarian carcinoma.¹

The association between residual tumor volume after primary cytoreduction and survival was less consistent in patients with low-grade serous ovarian carcinoma (LGSOC) compared to other histological types, highlighting variability in surgical outcomes across ovarian cancer subtypes. | Image Credit: Georgii - stock.adobe.com

The researchers analyzed patient data gathered from the National Cancer Database. Patients with stage III epithelial ovarian cancer who underwent primary cytoreductive surgery between 2011 and 2020 were included. They assessed the association of overall survival (OS) and residual disease after primary cytoreduction (complete cytoreduction [R0], optimal cytoreduction [R1], and suboptimal cytoreduction [R2]) with Cox proportional hazards regression models, adjusting for other demographic and clinical characteristics.

The study population consisted of 1100 patients with ovarian clear cell carcinoma (CCC), 495 with mucinous ovarian carcinoma (MOC), 1103 with LGSOC, and 13,046 with high-grade serous ovarian carcinoma (HGSOC). Compared with HGSOC (59.9%), complete cytoreduction rates were higher in less-common cancer types (MOC, 72.1%; LGSOC, 73.2%; CCC, 74.0%; P < .001).

Conversely, complete cytoreduction rates increased about 27.8% in patients with HGSOC during the study period (95% CI, 52.2-62.8; P < .001), but it did not increase in those with CCC (95% CI, 60.5-77.3; P = .32), MOC (95% CI, 60.0-70.7; P = .18), or LGSOC (95% CI, 67.0-70.1; P = .48). Across the 4 histology types, the number of primary cytoreductive surgical procedures decreased 41.6% from 1811 to 1057 procedures during the study period.

In those with HGSOC, the researchers determined that more extensive residual disease after primary cytoreduction was associated with lower 5-year OS. More specifically, the rates were 58.5% for R0, 45.0% for R1 (adjusted hazard ratio [aHR], 1.44; 95% CI, 1.36-1.52), and 36.2% for R2 (aHR, 1.77; 95% CI, 1.63-1.93).

As for the CCC and MOC cohorts, R0 was associated with improved 5-year OS rates. The 5-year OS rates for patients with CCC were 45.2% for R0, 25.9% for R1 (aHR, 1.72; 95% CI, 1.42-2.08), and 29.5% for R2 (aHR, 1.95; 95% CI, 1.35-2.81). Similarly, in patients with MOC, the 5-year OS rates were 40.5% for R0, 25.1% for R1 (aHR, 1.55; 95% CI, 1,17-2.07), and 26.3% for R2 (aHR, 1.63; 95% CI, 1.03-2.56).

However, the extent of cytoreduction did not significantly impact OS in patients with LGSOC. Therefore, the 5-year OS rates for this population were 80.8% for R0, 75.3% for R1 (aHR, 1.04; 95% CI, 0.75-1.45), and 63.0% for R2 (aHR, 1.19; 95% CI, 0.66-2.12).

The researchers acknowledged the study limitations, including unmeasured confounding and a lack of information on tumor complexity, burden, anatomical location, and the exact size of residual disease. They also noted that recurrence data were not available.

“Despite these limitations, the observed survival associations call for awareness of the distinct clinical and biological differences across epithelial ovarian carcinoma histological types, particularly for LGSOC,” the authors concluded.

References

1. Matsuo K, Chen L, Klar M, et al. Primary cytoreduction and survival for patients with less-common epithelial ovarian cancer. JAMA Netw Open. 2024;7(6):e2417775. doi:10.1001/jamanetworkopen.2024.17775
2. NCCN guidelines: ovarian cancer/fallopian tube cancer/primary peritoneal cancer. National Comprehensive Cancer Network. Accessed February 16, 2024. https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1453
3. Horowitz NS, Miller A, Rungruang B, et al. Does aggressive surgery improve outcomes—interaction between preoperative disease burden and complex surgery in patients with advanced-stage ovarian cancer: an analysis of GOG 182. J Clin Oncol. 2015;33(8):937-943. doi:10.1200/JCO.2014.56.3106