Médecine Nucléaire et Radiothérapie

Critical Normal Structures Doses for Non Small Cell Lung Cancer using 3-D Conformal Radiotherapy

Abstract

Karacetin Didem, Cakir Aydin, Karaman Sule, Kemikler Ebru, Tenekeci Nuri, Saglam K Esra, Oral Ethem Nezih and Kizir Ahmet

Purpose: In this prospective study, we have aimed to analyze the levels of doses and toxicities of critical normal structures in the treatment of non-small cell lung cancer (NSCLC) with 3-D Conformal Radiotherapy.

Material and Method: We have evaluated 24 patients with biopsy proven inoperable NSCLC stages III, treated with Conformal Radiotherapy. After CT- simulation, GTV, CTV, PTV and critical normal structures (lungs, esophagus, heart, and spinal cord) were contoured by the physician and radiologist and then dose volumes were calculated. Chemoradiotherapy was used in these patients after induction treatment. Induction chemotherapy was administrated: Docetaxe l75 mg/m² + Cisplatin 75 mg/m² from day 1 for each 21 days, total 3 cycles. After induction therapy concomitant Docetaxel 25 mg/m² + Cisplatin 25 mg/m² were administrated weekly for 5 to 6 weeks and radiotherapy was delivered with linear accelerator, 64 – 66 Gy/32 – 33 fr/200 cGy/d. The study endpoints were critical normal structures doses, early and late toxicities, and local control.

Results: DVH: Lungs V20 is 32%. Heart Dmean doses are 1892 cGy (Dmin 22 cGy - Dmax. 4084 cGy). Esophagus Dmean doses are 2700 cGy (Dmin. 912 cGy - Dmax. 4513 cGy) and Spinal cord Dmean is 1201 cGy (Dmin. 115 cGy - Dmax. 2139 cGy). Acute toxicities; 18 patients (75%) have grade I-II esophagitis, 6 patients (25%) have grade III esohagitis, 7 patients (29%) have grade III-IV pneumonia and 4 patients (16,6 %) have grade I-II pneumonia. No late toxicity has been observed in esophagus, heart and even lungs. Median follow-up was 13 months and local control rate was 41.6%.

Conclusion: This study confirms that 3-D Conformal Radiotherapy is an effective treatment with NSCLC. But patients in the study have large tumors or tumors near critical locations, so critical normal structures doses were high compared with literature.