Purpose: To evaluate the acute toxicity of simultaneous integrated boost (SIB) technique for dose escalation with helical tomotherapy (HT) in patients with locally advanced cervical cancer.
Patients and methods: 20 patients (FIGO IB1 pN1-IIIB) underwent primary chemoradiation. Prior to chemoradiation, a laparoscopic pelvic and para-aortic lymphadenectomy was performed. A boost region was defined using titanium clips during staging for planning target volume (PTV-B). Patients were treated with five weekly fractions of 1.8 Gy to a total dose of 50.4 Gy to the tumor region and the pelvic (para-aortic) lymph node region (PTV-A), and five weekly fractions of 2.12 Gy to a total dose of 59.36 Gy to the PTV-B. Chemotherapy consisted of weekly cisplatin 40 mg/m(2). 19 patients underwent brachytherapy. Dose-volume histograms were evaluated and acute gastrointestinal (GI), genitourinary (GU), and hematologic toxicity were documented (CTCAE v3.0).
Results: Pelvic and para-aortic lymph node metastases were confirmed in nine and four patients, respectively. Five patients refused laparoscopic staging. The mean volume of PTV-A and PTV-B was 1,570 ± 404 cm(3) and 341 ± 125 cm(3), respectively. The mean dose to the bladder, rectum, and small bowel was 47.85 Gy, 45.76 Gy, and 29.71 Gy, respectively. No grade 4/5 toxicity was observed. Grade 2/3 hematologic toxicity occurred in 50% of patients and 5% experienced grade 3 diarrhea. There was no grade 3 GU toxicity. 19 patients underwent curettage 6-9 weeks after chemoradiation without any evidence of tumor.
Conclusion: The concept of SIB for dose escalation in patients with locally advanced cervical cancer is feasible with a low rate of acute toxicity. Whether dose escalation can translate into improved outcome will be assessed after a longer follow-up.