Predictors of cardiac dose sparing in deep inspiratory breath-hold technique for radiation of left breast cancer patients.

Introduction: Radiation therapy to left breast cancer patients results in significant exposure to heart resulting in long-term cardiac morbidity. This exposure can be reduced by performing deep inspiratory breath-hold (DIBH) technique, however, patient selection criteria or predictive parameters are not routinely used which can identify patients who will have significant benefit with this technique. This study intends to find and use these predictive parameters measured on free-breathing (FB) simulation scan which can help to select such patients so as to develop our institutional protocol. Methods: A total of 35 patients of left breast cancer postsurgery were recruited in the study. All patients underwent 2-3 sessions of DIBH coaching followed by planning computed tomography scan in both FB phase and DIBH phase. Various anatomical parameters such as cardiac contact distance parasagittal (CCDps), CCD axial, heart-chest distance (HCD), and D were measured on FB scan and were correlated with a mean heart dose achieved in DIBH scan. Results: Dose to normal structures, namely heart and lung, was drastically reduced for DIBH scan over FB scan. V5, V10, and V20 of heart also followed a similar reduction. The mean dose to heart in FB scan was 5.34 Gy, while in DIBH scan, it was 2.79 Gy which was statistically significant. Among all the parameters measured, CCDps and D had a statistically significant positive correlation with the mean heart dose in DIBH phase while HCD had a negative correlation which was statistically significant. Conclusion: Cardiac parameters on FB scan such as CCDps, HCD, and D predict the patients with usual cardiac risk who will benefit most with DIBH techniques setting an arbitrarily cutoff value.

Dosimetric correlation of bone marrow irradiation with acute hematological toxicity in concurrent chemoradiation of cervical carcinoma patients.

Background: Many acute toxicities are associated with concurrent chemoradiation in cervical carcinoma, which includes burning micturition, burning defecation, pain lower abdomen, increased frequency of stools along with Acute Hematological Toxicity (AHT). AHT is often an expected adverse effect, which can lead to treatment interruptions and decreased response rates. The purpose of this study is to analyze if there are any dosimetric constraints on the volume of bone marrow irradiated with AHT in cervical carcinoma patients treated with concurrent chemoradiation. Material and Methods: In this retrospective study of 215 patients, a total of 180 patients were eligible for analysis. Multiple parameters of bone marrow volumes (whole pelvis bone marrow and its sub-volumes--ilium, lower pelvis, and lumbosacral spine) which were contoured individually for all patients were assessed to have any statistically significant association with AHT. Results: The median age of the cohort was 57 years and majority of cases were locally advanced (stage IIB-IVA: 88.3%). Grade I, II, III leukopenia was seen in 44, 25, and 6 patients, respectively. A statistically significant correlation between grade 2+ and 3+ leukopenia was seen if bone marrow V10, V20, V30, and V40 were more than 95%, 82%, 62%, and 38%, respectively. In subvolume analysis, volumes of lumbosacral spine V20, V30, and V40 more than 95%, 90%, and 65%, respectively, were statistically significant for AHT. Conclusion: Bone marrow volumes should also be given a constraint and should be tried to be achieved so that it leads to minimal treatment breaks due to AHT.

Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme.

Objectives: Image-guided radiotherapy maximizes therapeutic index of brain irradiation by reducing setup errors during treatment. The aim of study was to analyze setup errors in the radiation treatment of glioblastoma multiforme and if decrease in planning target volume (PTV), margin is feasible using daily cone beam CT (CBCT) and 6D couch correction. Materials and Methods: Twenty-one patients (630 fractions of radiotherapy) were studied in which corrections were made in 6° of freedom. We determined setup errors, impact of setup errors of initial three fractions CBCT versus rest of the treatment with daily CBCT, and mean difference in setup errors with or without application of 6D couch and volumetric benefit of reduction of PTV margin from 0.5 cm to 0.3 cm. Results: The mean shift in the conventional directions, namely, vertical, longitudinal, and lateral was 0.17 cm, 0.19 cm, and 0.11 cm. There was significant change in vertical shift when first three fractions were compared with rest of the treatment with daily CBCT. When the effect of 6D couch was nullified, all directions showed increased error with longitudinal shift being significant. The number of setup errors of magnitude >0.3 cm was more significant when only conventional shifts were applied as compared with 6D couch. There was significant decrease in volume of brain parenchyma irradiated when margin of PTV was reduced from 0.5 cm to 0.3 cm. Conclusion: Daily CBCT along with 6D couch correction can reduce setup error which allows reduction in PTV margin during radiotherapy planning in turn improving the therapeutic index.

Impact of sarcopenia in locally advanced head and neck cancer treated with chemoradiation: An Indian tertiary care hospital experience.

BACKGROUND: Sarcopenia is emerging as a poor prognostic factor in terms of treatment outcome as well as complications in cancer patients. This study aims to determine the prevalence of sarcopenia and its impact on outcome and toxicity in head and neck squamous cell carcinoma (HNSCC) patients treated with definitive chemo radiotherapy. MATERIAL AND METHODS: Three hundred patients of locally advanced HNSCC were included. All patients were treated with radical radiotherapy dose of 70 Gy/35# over 7 weeks along with concurrent chemotherapy. Sarcopenia was assessed from radiation planning computed tomography (CT) scans using skeletal muscle mass at level C3. The impact of sarcopenia on treatment outcome, Disease Free Survival (DFS) and toxicity was evaluated. Association between patient factors and outcome was calculated in univariate and multivariate analyses. RESULTS: Sarcopenic patients were more likely to be elderly, female gender and hypopharyngeal primary. The average SMI of the entire patient cohort was 31.9 cm2/m2 and for males and females were 32.78 cm2/m2 and 26.19 cm2/m2 respectively. As per cut of criteria used nearly 91% of the patient cohort were sarcopenic. Sarcopenic patients had a worse treatment outcome namely poorer disease free survival, more toxicities and more treatment gaps. As per ROC curve patients with SMI of >32 cm2/m2 fared better than those with SMI < 32 cm2/m2. CONCLUSION: Sarcopenia in HNSCC patients receiving definitive chemo radiotherapy is an independent prognostic factor and is associated with a worse treatment outcome and more toxicities.