R. Matute

Helical tomotherapy in the treatment of pediatric malignancies: a preliminary report of feasibility and acute toxicity

BackgroundRadiation therapy plays a central role in the management of many childhood malignancies and Helical Tomotherapy (HT) provides potential to decrease toxicity by limiting the radiation dose to normal structures. The aim of this article was to report preliminary results of our clinical experience with HT in pediatric malignancies.MethodsIn this study 66 consecutive patients younger than 14 years old, treated with HT at our center between January 2006 and April 2010, have been included. We performed statistical analyses to assess the relationship between acute toxicity, graded according to the RTOG criteria, and several clinical and treatment characteristics such as a dose and irradiation volume.ResultsThe median age of patients was 5 years. The most common tumor sites were: central nervous system (57%), abdomen (17%) and thorax (6%). The most prevalent histological types were: medulloblastoma (16 patients), neuroblastoma (9 patients) and rhabdomyosarcoma (7 patients). A total of 52 patients were treated for primary disease and 14 patients were treated for recurrent tumors. The majority of the patients (72%) were previously treated with chemotherapy. The median prescribed dose was 51 Gy (range 10-70 Gy). In 81% of cases grade 1 or 2 acute toxicity was observed. There were 11 cases (16,6%) of grade 3 hematological toxicity, two cases of grade 3 skin toxicity and one case of grade 3 emesis. Nine patients (13,6%) had grade 4 hematological toxicity. There were no cases of grade 4 non-hematological toxicities. On the univariate analysis, total dose and craniospinal irradiation (24 cases) were significantly associated with severe toxicity (grade 3 or more), whereas age and chemotherapy were not. On the multivariate analysis, craniospinal irradiation was the only significant independent risk factor for grade 3-4 toxicity.ConclusionHT in pediatric population is feasible and safe treatment modality. It is characterized by an acceptable level of acute toxicity that we have seen in this highly selected pediatric patient cohort with clinical features of poor prognosis and/or aggressive therapy needed. Despite of a dosimetrical advantage of HT technique, an exhaustive analysis of long-term follow-up data is needed to assess late toxicity, especially in this potentially sensitive to radiation population.

Ethnic difference in risk of toxicity in prostate cancer patients treated with dynamic arc radiation therapy

Aims and background The objective of this study was to assess the influence of ethnicity on toxicity in patients treated with dynamic arc radiation therapy (ART) for prostate cancer (PC). Methods From June 2006 to May 2012, 162 cT1-T3 cN0 cM0 PC patients were treated with ART (primary diagnosis, n = 125; post-prostatectomy/brachytherapy biochemical recurrence, n = 26; adjuvant post-prostatectomy, n = 11) at 2 institutions. Forty-five patients were Latin Americans and 117 were Europeans. The dose prescribed to the prostate ranged between 68 Gy and 81 Gy. Results The median age was 69 years (range 43-87 years). The median follow-up was 18 months (range 2-74 months). Overall, only 3 patients died, none due to a cancer-related cause. Biochemical recurrence was seen in 7 patients. The rates of acute grade 2 gastrointestinal (GI) and genitourinary (GU) toxicities were 19.7% and 17%, respectively. Only 1 patient experienced acute grade 3 GI toxicity, whereas 11 patients (6.7%) experienced acute grade 3 GU toxicity. Multivariate analysis showed that undergoing whole pelvic lymph node irradiation was associated with a higher grade of acute GI toxicity (OR: 3.46; p = 0.003). In addition, older age was marginally associated with a higher grade of acute GI toxicity (OR: 2.10; p = 0.074). Finally, ethnicity was associated with acute GU toxicity: Europeans had lower-grade toxicity (OR: 0.27; p = 0.001). Conclusions Our findings suggest an ethnic difference in GU toxicity for PC patients treated with ART. In addition, we found that ART is associated with a very low risk of severe toxicity and a low recurrence rate.

Image-Guided Radiation Therapy Based on Helical Tomotherapy in Prostate Cancer: Minimizing Toxicity

Background: We report the clinical results and prognostic factors of image-guided radiation therapy (RT) with helical tomotherapy (HT) for localized and recurrent prostate cancer (PC). Patients and Methods: We evaluated 70 patients with PC (primary diagnosis, n = 48; adjuvant, n = 5; salvage, n = 17) treated with HT from May 2006 through January 2011. The dose prescribed to the prostate/surgical bed ranged between 60 and 78 Gy. Potential risk factors for genitourinary (GU) and gastrointestinal (GI) toxicity were assessed. Results: The median age was 68 years (range 51-87 years). The median follow-up was 37 months (range 3-74 months). The rates of acute grade 2 GI and GU toxicities were 10 and 13%, respectively. Only 1 patient experienced acute grade 3 GU toxicity. The rates of late grade ≥ 2 GI and GU toxicities were 1% each. Multivariate analysis showed an association between rectum mean dose > median (39 Gy) and bladder median dose > median (46 Gy) with a higher grade of acute GI (p = 0.017) and GU (p = 0.019) toxicity, respectively. Additionally, older age was associated with late GU toxicity (p = 0.026). Conclusion: Toxicity with HT is low and is associated with higher median/mean doses in organs at risk as well as with older age. A prospective validation would be necessary to confirm these results.