Ben Slotman

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Disparities in access to radiation therapy for regions inhabited by a higher proportion of First Nations, Inuit and Métis populations in Canada, and its association with cancer outcomes

Applied Radiation Oncology

Background: First Nations, Inuit and Métis (FNIM) peoples in Canada exhibit high rates of cancer ... more Background: First Nations, Inuit and Métis (FNIM) peoples in Canada exhibit high rates of cancer mortality. Little information exists on access to radiation therapy (RT) among these populations. We sought to describe geographic access to RT, and to explore its relationship with cancer outcomes among regions inhabited by a higher proportion of FNIM peoples in Canada. Methods and Materials: We calculated the linear distance from the centroid of each Canadian health region to the nearest RT center using a geographic analytical techniques, and compared distance between regions with a higher (≥ 23%) vs lower (< 23%) proportion of FNIM peoples (self-identified as Aboriginals through census data from Statistics Canada). We examined relationships between distance and proportion of FNIM peoples on cancer outcomes in an initial exploratory analysis, using age-standardized all-cancer mortality-to-incidence ratios (MIRs) from 2010 to 2012. A prediction model based on recursive partitioning was created, and the resulting groups were compared using one-way analyses of variance and nonparametric tests. Results: Health regions inhabited by a higher proportion of FNIM peoples were located further from RT centers (799 vs 120 km, p < .0001), and had worse cancer outcomes (MIR 0.53 vs 0.42, p < .0001). Among a subset of overlapping regions 150-750 km from RT centers, those with a higher proportion of FNIM peoples had worse outcomes (MIR 0.50 vs 0.44, p = .03), despite a similar distance (p = .47). In our prediction model, distance to an RT center had the largest impact on MIR, followed equally by smoking and proportion of FNIM peoples. Regions closer to RT centers with a higher proportion of FNIM peoples had poor outcomes that did not differ from regions furthest away (p = .41), and showed a trend toward worse outcomes compared to regions with a lower proportion of FNIM peoples within the same distance (p = .07). Conclusions: Regions inhabited by a higher proportion of FNIM populations are further away from RT centers and have poorer outcomes. Distance is an important factor but does not completely explain these regions' poorer cancer outcomes.

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Relationship between Treatment Plan Dosimetry, Toxicity, and Survival following Intensity-Modulated Radiotherapy, with or without Chemotherapy, for Stage III Inoperable Non-Small Cell Lung Cancer

Cancers

Concurrent chemoradiotherapy (cCRT) is the preferred treatment for stage III NSCLC because surger... more Concurrent chemoradiotherapy (cCRT) is the preferred treatment for stage III NSCLC because surgery containing multimodality treatment is often not appropriate. Alternatives, often for less fit patients, include sequential CRT and RT alone. Many reports describing the relationship between overall survival (OS), toxicity, and dosimetry are based on clinical trials, with strict criteria for patient selection. We performed an institutional analysis to study the relationship between dosimetric parameters, toxicity, and OS in inoperable patients with stage III NSCLC treated with (hybrid) IMRT/VMAT-based techniques in routine clinical practice. Eligible patients had undergone treatment with radical intent using cCRT, sCRT, or RT alone, planned to a total dose ≥ 50 Gy delivered in ≥15 fractions. All analyses were performed for two patient groups, (1) cCRT (n = 64) and (2) sCRT/RT (n = 65). The toxicity rate differences between the two groups were not significant, and OS was 29 and 17 months...

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