Abstract
Standard radiation therapy for patients undergoing primary chemosensitized radiation for carcinomas of the cervix usually consists of external beam radiation followed by an intracavitary brachytherapy boost. On occasion, the brachytherapy boost cannot be performed due to unfavorable anatomy or because of coexisting medical conditions. We examined the safety and efficacy of using CyberKnife stereotactic body radiotherapy (SBRT) as a boost to the cervix after external beam radiation in those patients unable to have brachytherapy to give a more effective dose to the cervix than with conventional external beam radiation alone. Six consecutive patients with anatomic or medical conditions precluding a tandem and ovoid boost were treated with combined external beam radiation and CyberKnife boost to the cervix. Five patients received 45 Gy to the pelvis with serial intensity-modulated radiation therapy boost to the uterus and cervix to a dose of 61.2 Gy. These five patients received an SBRT boost to the cervix to a dose of 20 Gy in five fractions of 4 Gy each. One patient was treated to the pelvis to a dose of 45 Gy with an external beam boost to the uterus and cervix to a dose of 50.4 Gy. This patient received an SBRT boost to the cervix to a dose of 19.5 Gy in three fractions of 6.5 Gy. Five percent volumes of the bladder and rectum were kept to ≤75 Gy in all patients (i.e., V75 Gy ≤ 5%). All of the patients remain locally controlled with no evidence of disease following treatment. Grade 1 diarrhea occurred in 4/6 patients during the conventional external beam radiation. There has been no grade 3 or 4 rectal or bladder toxicity. There were no toxicities observed following SBRT boost. At a median follow-up of 14 months, CyberKnife radiosurgical boost is well tolerated and efficacious in providing a boost to patients with cervix cancer who are unable to undergo brachytherapy boost. Further follow-up is required to see if these results remain durable.
Highlights
Standard radiation therapy for cervical carcinoma patients undergoing primary chemosensitized radiation therapy usually consists of external beam therapy followed by an intracavitary brachytherapy boost (Eifel et al, 2004)
We examined the safety and efficacy of using CyberKnife stereotactic body radiotherapy (SBRT) as a boost to the cervix after external beam radiation in those patients unable to have brachytherapy to give a more effective dose to the cervix than with conventional external beam radiation alone
We present preliminary local control results on the treatment of six patients with cervical cancer who did not have a brachytherapy boost and were treated with an SBRT boost resulting in a total dose of 77–85 Gy to the cervix
Summary
Standard radiation therapy for cervical carcinoma patients undergoing primary chemosensitized radiation therapy usually consists of external beam therapy followed by an intracavitary brachytherapy boost (Eifel et al, 2004). The brachytherapy boost may not be feasible due to coexisting medical conditions, unfavorable anatomy, or patient refusal to undergo the procedure In these cases, a higher dose of external beam radiation (EBRT) may be given, but the total dose delivered is usually less than when a brachytherapy procedure is performed. The majority of patients developed a central recurrence in less than 5 years and had a 5year overall survival rate of 49.3% (Barraclough et al, 2008) This compares unfavorably to combined external beam therapy with a brachytherapy boost where 5-year local control and survival are in the 60–70% range (Rose et al, 1999; Eifel et al, 2004)
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