[Application value of reduced field intensity modulated radiation therapy for advanced cervical cancer]

To explore the clinical value and efficacy of reduced field intensity modulated radiation therapy (RF-IMRT) for patients with advanced cervical cancer.

Seventy-one patients with stage IIB-IIIB cervical cancer, who underwent reduced field IMRT (RF-IMRT group) and 72 patients treated with conventional radiotherapy (c-RT group) in Shandong Cancer Hospital between 2005 August and 2011 August, were enrolled in this study. The RF-IMRT plans were as follows: whole pelvic IMRT plan was performed to deliver an initial dose of 30 Gy, then the irradiated volume was reduced to lymphatic drainage region as well as paracervix and parametrium for an additional 30 Gy boost. Conventional 2-field RT plan was performed in these patients using ADAC Pinnacle 3 planning system, to be given the same prescription dose, and to compare the irradiation dose of organs at risk (OARs). At the same time, conventional 2-field RT was performed in 72 patients of the c-RT group. Concurrent chemotherapy and intracavitary brachytherapy were also performed in the two groups. The treatment response, toxicities, normal tissue avoidance, and survival were assessed.

Sixty-six patients of the RF-IMRT group and 65 patients of the c-RT group fulfilled the treatment plan. IMRT plans yielded better dose conformity to the target (0.711 ± 0.057 vs. 0.525 ± 0.062, P = 0.032) and better sparing of the rectum, bladder and small intestine (rectum: 41.6 ± 6.8 vs. 50.8 ± 3.2, P = 0.016; bladder: 40.2 ± 2.9 vs. 51.4 ± 1.8, P = 0.007; small intestine: 22.3 ± 2.6 vs. 35.8 ± 3.9, P = 0.004). The mean dose delivered to the planning target volume (PTV) was significantly higher in the RF-IMRT group than that in the c-RT group (60.8 vs. 51.2 Gy, P = 0.006). The RF-IMRT patients experienced significantly lower acute and chronic toxicities with comparable short-term effects than did those treated with conventional RT (P > 0.05). No significant differences were found between the two groups for 1-, 3-, and 5-year overall survival (OS) rates, while a significantly higher progression-free survival (PFS, 65.2% vs. 46.2%, P = 0.031) rate was observed in the RF-IMRT group.

RF-IMRT yields higher dose distributions and lower toxicities compared with conventional RT, and both the tumor target volume and pelvic lymphatic drainage region achieve curative dose irradiation, the adjacent organs at risk are well protected, and with tolerable adverse reactions. Yet, RF-IMRT provides comparable clinical outcomes and higher PFS.