Radiat Oncol J.  2017 Dec;35(4):368-379. 10.3857/roj.2017.00227.

Dosimetric advantages and clinical outcomes of simultaneous integrated boost intensity-modulated radiotherapy for anal squamous cell carcinoma

• Sakanaka K
• Itasaka S
• Ishida Y
• Fujii K
• Horimatsu
• Mizowaki T
• Sakai Y
• Hiraoka M

• KMID: 2401791
• DOI: http://doi.org/10.3857/roj.2017.00227

Abstract

PURPOSE
The purpose of this study was to explore the dosimetric difference between simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) and three-dimensional conformal radiotherapy (3DCRT), and the clinical outcomes of anal squamous cell carcinoma (ASCC) chemoradiotherapy featuring SIB-IMRT.
MATERIALS AND METHODS
This study included ten patients with ASCC who underwent chemoradiotherapy using SIB-IMRT with 5-fluorouracil and mitomycin C. SIB-IMRT delivered 54 Gy to each primary tumor plus metastatic lymph nodes and 45 Gy to regional lymph nodes, in 30 fractions. Four patients received additional boosts to the primary tumors and metastatic lymph nodes; the median total dose was 54 Gy (range, 54 to 60 Gy). We additionally created 3DCRT plans following the Radiation Therapy Oncology Group 9811 protocol to allow dosimetric comparisons with SIB-IMRT. Locoregional control, overall survival, and toxicity were calculated for the clinical outcome evaluation.
RESULTS
Compared to 3DCRT, SIB-IMRT significantly reduced doses to the external genitalia, bladder, and intestine, delivering the doses to target and elective nodal region. At a median follow-up time of 46 months, 3-year locoregional control and overall survival rates were 88.9% and 100%, respectively. Acute toxicities were treated conservatively. All patients completed radiotherapy with brief interruptions (range, 0 to 2 days). No patient experienced ≥grade 3 late toxicity during the follow-up period.
CONCLUSION
The dosimetric advantages of SIB-IMRT appeared to reduce the toxicity of chemoradiotherapy for ASCC achieving high locoregional control in the extended period.

Keyword

Anus neoplasms; Chemoradiotherapy; Intensity-modulated radiotherapy; Computer-assisted radiotherapy planning; Treatment outcome

MeSH Terms

Anus Neoplasms
Carcinoma, Squamous Cell*
Chemoradiotherapy
Epithelial Cells*
Fluorouracil
Follow-Up Studies
Genitalia
Humans
Intestines
Lymph Nodes
Mitomycin
Radiotherapy
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Conformal
Radiotherapy, Intensity-Modulated*
Survival Rate
Treatment Outcome
Urinary Bladder
Fluorouracil
Mitomycin