Heterogeneous treatment effects of adjuvant therapy for patients with cervical cancer in the intermediate-risk group

The efficacy of adjuvant therapy for patients with cervical cancer with intermediate risk (CC-IR) remains controversial. We examined the impact of adjuvant therapy on survival outcomes in patients with CC-IR and evaluated the heterogeneous treatment effects (HTEs) of adjuvant therapies based on clinicopathologic characteristics.

We retrospectively analyzed a previous Japanese nationwide cohort of 6192 patients with stage IB-IIB cervical cancer who underwent radical hysterectomy. We created two pairs of propensity score-matched treatment/control groups to investigate the treatment effects of adjuvant therapies: (1) adjuvant therapy versus non-adjuvant therapy; (2) chemotherapy versus radiotherapy conditional on adjuvant therapy. Multivariate analyses with treatment interactions were performed to evaluate the HTEs.

Among the 1613 patients with CC-IR, 619 and 994 were in the non-treatment and treatment groups, respectively. Survival outcomes did not differ between the two groups: 3-year progression-free survival (PFS) rates were 88.1% and 90.3% in the non-treatment and treatment groups, respectively (p = 0.199). Of the patients in the treatment group, 654 and 340 received radiotherapy and chemotherapy, respectively. Patients who received chemotherapy had better PFS than those who received radiotherapy (3-year PFS, 90.9% vs. 82.9%, p = 0.010). Tumor size was a significant factor that affected the treatment effects of chemotherapy; patients with large tumors gained better therapeutic effects from chemotherapy than those with small tumors.

Adjuvant therapy is optional for some patients with CC-IR; however, chemotherapy can be recommended as adjuvant therapy, particularly for patients with large tumors.