Radiation induced pneumonitis following whole breast radiotherapy treatment in early breast cancer patients treated with breast conserving surgery: a single institution study

BACKGROUND

Hypofractionated Radiotherapy (RT) regimens for breast cancer, although reduce cost and time for patients and health care systems, could have a negative impact on normal underlying lung tissue. We studied and compared lung function and the post-RT radiological changes using High-Resolution Computed Tomography (HRCT) in early breast cancer patients, treated with 3-Dimentional conformal whole breast radiotherapy (WBRT) using either conventional or hypofractionated regime.

PATIENTS AND METHODS

Between 2008 and 2009, 61 early breast cancer patients (T1-2N0M0) were randomised into two groups .Group A (n=31) received standard radiotherapy with 50Gy/25f/5w plus boost 10Gy/5f/1w to tumour bed. Group B (n=30) received 43.2Gy/16f/22d plus boost 10Gy/5f/1w to tumour bed. Patients of both groups were subjected to dynamic lung testing, using spirometry and gas diffusion tests on Day 0 (D0, before RT), during RT and after completion of RT at 3 and 6 months. HRCT scans were performed in all patients at baseline, and 3,6,12 months after completion of RT. Respiratory symptoms were recorded at 3 and 6 months post completion of RT. Dosimetric factors, such as Central Lung Dose (CLD), lung Volume receiving more 20 Gy (V20), D25 and Mean Lung Dose (MLD) were calculated for all patients.

RESULTS

At 3 months after RT, the pulmonary changes were classified at HRCT as follows: 91.8 % were Grade 0, 8.19 % Grade 1, and 0 % Grade 2. At 6 months, 86.98 % were Grade 0, 11.47 % Grade 1, and 1.6 % Grade 2. At 12 months, 88.52 % were Grade 0, 9.19 % Grade 1 and 3.27% Grade 2. Univariate analysis showed strong association between radiation pneumonitis, age and all dosimetric parameters. There was no association between fractionation type and incidence of RN. FEV1, FVC, FEV 25, FEV 50 and DLCO showed no statistically significant reduction in both treatment groups in 3 and 6 months following completion of RT, compared to baseline. Multivariate analysis showed no relation between HRCT findings and other variables (age, smoking, chemotherapy, hormonotherapy, V20).

CONCLUSION

Lung toxicity, as assessed with HRCT and PFTs, was minimal in both treatment arms and our results are in consistency with other published data. Hypofractionated RT was a safe modality and well tolerated by the majority of the patients. Longer follow-up is required for robust assessment of incidence of late lung fibrosis in our series.

Long-term follow-up confirms the efficacy of linac radiosurgery for acoustic neuroma and meningioma patients. A single institution's experience

PURPOSE

To investigate the long-term efficacy and toxicity in a group of consecutive patients treated with linear accelerator (linac) radiosurgery for acoustic neuromas and meningiomas.

METHODS

Between 2000 and 2004, 34 patients (median age 65.5 years, range 50-84) with acoustic neuroma or meningioma were treated with linac-based stereotactic radiosurgery with a surface dose of 11-15.5 Gy. The maximum lesion diameter ranged from 10 to 34 mm. Median tumor volume was 5.95cm(3). The follow-up consisted of repeated imaging studies and clinical examination in the first 6 and 12 months after the intervention and yearly thereafter.

RESULTS

Follow-up time ranged from 50 to 99 months (median 75). Nineteen (59%) tumors decreased in size and 13 (41%) remained stable. None of the tumors increased in size in the long-term follow-up, resulting in an overall growth control of 100% for the small number of patients of our study. No patient developed new permanent facial or trigeminal neuropathy or deterioration of preexisting symptoms.

CONCLUSION

Long-term follow-up confirms the efficacy and low toxicity of linac radiosurgery for neuroma and meningioma patients.

Narrow stereotactic beam profile measurements using N-vinylpyrrolidone based polymer gels and magnetic resonance imaging

In this work, polymer gel-MRI dosimetry (using VIPAR gels), radiographic film and a PinPoint ion chamber were used for profile measurements of 6 MV x-ray stereotactic beams of 5 and 10 mm diameter. The VIPAR gel-MRI method exhibited a linear dose response up to 32 Gy. VIPAR gels were found to resolve the penumbra region quite accurately, provided that the in-plane image resolution of the related T2-map is adequate (< or = 0.53 mm). T2-map slice thickness had no significant effect on beam profile data. VIPAR measurements performed with a spatial resolution of 0.13 mm provided penumbra widths (80%-20% distance) of 1.34 and 1.70 mm for the 5 and 10 mm cones respectively. These widths were found to be significantly smaller than those obtained with the film (2.23 mm for the 5 mm cone, 2.45 mm for the 10 mm cone) and PinPoint (2.25 mm for the 5 mm cone, 2.52 mm for the 10 mm cone) methods. Regarding relative depth dose measurements, good correlation between VIPAR gel and PinPoint data was observed. In conclusion, polymer gel-MRI dosimetry can provide relatively accurate profile data for very small beams used in stereotactic radiosurgery since it can overcome, to some extent, the problems related to the finite size of conventional detectors.