Intensity-modulated radiation therapy versus para-aortic field radiotherapy to treat para-aortic lymph node metastasis in cervical cancer: prospective study

Abstract

Aim: To compare dosimetry, efficacy, and toxicity of intensity-modulated radiation therapy (IMRT) with para-aortic field radiotherapy in patients with para-aortic lymph node (PALN) metastasis of cervical cancer.

Methods: This prospective study examined 60 patients with cervical cancer with PALN metastasis who underwent whole-pelvis radiotherapy followed by brachytherapy between November 1, 2004 and May 31, 2008. After 3 cycles of chemotherapy, patients were serially allocated into two groups and treated with IMRT or para-aortic field RT at doses of 58-68 Gy and 45-50 Gy, respectively. Treatment response was evaluated and toxicities were assessed. Patients in the IMRT group were treated with both para-aortic field RT and IMRT in order to compare the exposure dose of organs at risk.

Results: In the IMRT group, the mean dose delivered to the planning target volume was 67.5 Gy. At least 99% of the gross tumor volume received effective coverage and radical dose (median, 63.5 Gy; range, 54.5-66) during treatment. IMRT plans yielded better dose conformity to the target and better sparing of the spinal cord and small intestine than para-aortic field RT. The IMRT patients experienced less acute and chronic toxicities. The IMRT group also had higher 2- and 3-year survival rates than the para-aortic RT group (2-year, 58.8% vs 25.0%, P = 0.019; 3-year, 36.4% vs 15.6%, P = 0.016). However, no significant difference was found in 1-year survival (67.7% vs 51.3%, P =0.201). The median survival in the IMRT group was 25 months (range, 3 to 37 months). The actuarial overall survival, disease-free survival, and locoregional control rates at 2 years were 67%, 77%, and 88%, respectively, in the IMRT group.

Conclusions: IMRT provides better clinical outcomes than para-aortic field radiotherapy in patients with PALN metastasis. However, cervical local and distal recurrence remain a problem. Long-term follow-up and studies involving more patients are needed to confirm our results.

Figure 1

Isodose curves of a cross section, sagittal section, and coronary section of one representative patient for intensity-modulated radiation therapy (A) and one patient for para-aortic field radiotherapy (B).

Figure 2

Dose-volume histogram (DVH) of a representative patient for intensity-modulated radiation therapy (A) and para-aortic field radiotherapy (B): dash-double dot-dash – gross tumor volume; dash-dot-dash – planning target volume; dots – right kidney; em dashes – left kidney; solid line – spinal cord; en dashes – small intestine.

Figure 3

Kaplan-Meier survival curve showing overall survival for patients with recurrent cervical cancer: broken line – intensity-modulated radiation therapy group; dotted line – para-aortic field radiotherapy group.