ABSTRACT
Oligometastases is a term commonly used to describe a disease state characterized by a limited number of distant metastases, and represents a transient phase between localized and widespread systemic diseases. This subgroup of stage IV cancer has increased in clinical importance due to the possibility of curative rather than palliative treatment. Among advanced lung cancer patients, 30-40% show bone metastases, and can show complications such as pathological fractures. Many prospective studies have shown efficacy of localized treatment in oligometastatic non-small cell lung cancer (NSCLC) in improving progression-free survival and overall survival. Compared to metastases in other organs, bone metastases are unique in terms of tumor microenvironment and clinical outcomes. Radiotherapy is the most frequently used treatment modality for local ablative treatment for both primary and metastatic lesions. Stereotactic body radiation therapy demonstrated more rapid and effective pain control compared to conventional 3D conformal radiotherapy. Radiotherapy improved outcomes in terms of time-to-skeletal related events skeletal-related events (SRE), hospitalization for SRE, pain relief, and overall survival in patients with bone metastases. Decision on timing of local ablative treatment depends on patient's overall clinical status, treatment goals, potential side effects of each approach, and expected initial responses to systemic anti-cancer treatment.
ABSTRACT
BACKGROUND: The purpose of this study was to determine the α/ß ratio for normal liver with hepatitis by analyzing the toxicity data from patients with unresectable hepatocellular carcinoma treated with helical tomotherapy. METHODS: Between March 2006 and February 2012, 98 patients were eligible for this study. 66 patients received 45-50 Gy in 4.5-5 Gy fractions (Group A) and 32 patients received 36-60 Gy in 2.5-3 Gy fractions (Group B). Radiation-induced hepatic toxicity was defined as an increase of at least 2 points in the Child-Pugh score within 4 months of completing helical tomotherapy. We attempted to find the statistically significant parameters in the 2 groups using α/ß ratios of 2, 4, 6, 8, or 10, and compared the estimated probability curves of each significant parameter. We hypothesized that the α/ß ratio associated with the best matches for the curves between the 2 groups would be equivalent to the α/ß ratio for the normal liver. RESULTS: When using an α/ß ratio of 2 or 4, different parameters were found to be statistically significant in a multivariate analysis (Group A: VBED30 for α/ß ratio=2 and VBED25 for α/ß ratio=4, Group B: VBED25 for α/ß ratio=2 and VBED20 for α/ß ratio=4). When using an α/ß ratio of 6, 8, or 10, VBED20 was found to be a statistically significant parameter in both groups. Comparison of the estimated probability curve of each significant parameter between the groups revealed that an α/ß ratio of 8 resulted in the best matches. CONCLUSIONS: We suggest that the α/ß ratio of the normal liver with hepatitis is 8. We hope that previously reported parameters and their values can be effectively used in different fractionation schemes by calculating the biologically effective dose using an α/ß ratio of 8.
