3-Dimensional Conformal versus Intensity Modulated Radiotherapy in Head and Neck Squamous Cell Carcinoma: Comparative Analysis of Compliance, Toxicities and Dosimetric Parameters

Abstract

Introduction: Advance radiotherapy conformal techniqueshave an advantage over conventional radiotherapy in deliveringthe dose more accurately to the target volume while limiting thedoses to organs at risk. 3-dimensional conformal radiotherapyleads to sparing the surrounding normal tissue better than2-dimensional radiotherapy, but it still causes significantvolumes of normal tissue irradiation because RT is deliveredin three dimensions with a uniform dose in each field. Intensitymodulated radiotherapy is a refinement of 3-dimensionalconformal radiotherapy, which modulates the radiation beamsso that a high dose can be delivered to the tumor target while thedose to normal tissues can be reduced. The dose-modulatingability of IMRT gives a theoretical advantage over 3D-CRT,but it also has a drawback of delivering a higher dose outsidethe planning target volume (PTV) due to more number offields used. The present study aims to analyze and comparedosimetric parameters, compliance, and toxicities of thesetwo techniques.Materials and methods: About 50 patients of head neckcancers presented in our department were treated withdefinitive concurrent chemoradiation after randomizing intotwo groups of twenty-five each- Group I (3DCRT) and Group II(IMRT). Inclusion Criteria- Histologically proven squamous cellcarcinoma; age >18 years; Karnofsky performance status >70;normal hemogram, renal function test, liver function test and 2DECHO. Exclusion Criteria - prior or synchronous malignancy orprevious history of head and neck surgery; distant metastasis;previously treated patients with radiotherapy. Radiotherapydose of 70 Gy in 35 fractions over 7 weeks, along with weeklycisplatin 35 mg/m2, was given. Treatment compliance (overalltreatment time and number of weekly chemotherapy cycles),toxicities (hematological and radiotherapy-induced), clinicalresponse assessment and dosimetric parameters of PTVand organ at risk were compared. Statistical analysis wasdone using an unpaired t-test to compare the mean of twoindependent groups and a chi-square test for compliance andtoxicities.Results: The mean and median age in Group I is 57.2 years(35–77 years) and 60 years and in Group II is 62.08 years(42–76 years) and 63 years. The male-to-female ratio in groupsI and II is 11.5 and 5.25, respectively. The majority of the caseswere locoregionally advanced, 76% in Group I and 84% inGroup II. There was no statistically significant difference inoverall treatment time above 51 days in both groups (40 vs 24%)and patients receiving 5 to 7 cycles of chemotherapy (54 vs46%). Similarly, there was no statistically significant differencein hematological and radiotherapy-induced toxicities. Completeresponse seen in both groups (80 vs 72%, p = 0.51). The PTVparameters were achieved in both groups, but were statisticallybetter in IMRT. Dose constraints for OARs were achieved inmost organs, though they were statistically better in IMRT.Conclusion: Both techniques, 3-DCRT and IMRT, did nothave any statistical difference in treatment compliance andtoxicities. Dosimetric parameters were achievable, though theywere better in IMRT. Different forward planning techniques mayimprove and make 3DCRT plans comparable to IMRT