Non-Hodgkin lymphoma (NHL) comprises biologically and clinically heterogeneous subtypes. Previously, study size has limited the ability to compare and contrast the risk factor profiles among these heterogeneous subtypes. We pooled individual-level data from 17 471 NHL cases and 23 096 controls in 20 case–control studies from the International Lymphoma Epidemiology Consortium (InterLymph). We estimated the associations, measured as odds ratios, between each of 11 NHL subtypes and self-reported medical history, family history of hematologic malignancy, lifestyle factors, and occupation. We then assessed the heterogeneity of associations by evaluating the variability (Q value) of the estimated odds ratios for a given exposure among subtypes. Finally, we organized the subtypes into a hierarchical tree to identify groups that had similar risk factor profiles. Statistical significance of tree partitions was estimated by permutation-based P values (P_NODE). Risks differed statistically significantly among NHL subtypes for medical history factors (autoimmune diseases, hepatitis C virus seropositivity, eczema, and blood transfusion), family history of leukemia and multiple myeloma, alcohol consumption, cigarette smoking, and certain occupations, whereas generally homogeneous risks among subtypes were observed for family history of NHL, recreational sun exposure, hay fever, allergy, and socioeconomic status. Overall, the greatest difference in risk factors occurred between T-cell and B-cell lymphomas (P_NODE < 1.0×10⁻⁴), with increased risks generally restricted to T-cell lymphomas for eczema, T-cell-activating autoimmune diseases, family history of multiple myeloma, and occupation as a painter. We further observed substantial heterogeneity among B-cell lymphomas (P_NODE < 1.0×10⁻⁴). Increased risks for B-cell-activating autoimmune disease and hepatitis C virus seropositivity and decreased risks for alcohol consumption and occupation as a teacher generally were restricted to marginal zone lymphoma, Burkitt/Burkitt-like lymphoma/leukemia, diffuse large B-cell lymphoma, and/or lymphoplasmacytic lymphoma/Waldenström macroglobulinemia. Using a novel approach to investigate etiologic heterogeneity among NHL subtypes, we identified risk factors that were common among subtypes as well as risk factors that appeared to be distinct among individual or a few subtypes, suggesting both subtype-specific and shared underlying mechanisms. Further research is needed to test putative mechanisms, investigate other risk factors (eg, other infections, environmental exposures, and diet), and evaluate potential joint effects with genetic susceptibility.

Purpose: Palliative sedation is a clinical procedure aimed at relieving refractory symptoms in patients with advanced cancer. It has been suggested that sedative drugs may shorten life, but few studies exist comparing the survival of sedated and nonsedated patients. We present a systematic review of literature on the clinical practice of palliative sedation to assess the effect, if any, on survival. Methods: A systematic review of literature published between January 1980 and December 2010 was performed using MEDLINE and EMBASE databases. Search terms included palliative sedation, terminal sedation, refractory symptoms, cancer, neoplasm, palliative care, terminally ill, end-of-life care, and survival. A manual search of the bibliographies of electronically identified articles was also performed. Results: Eleven published articles were identified describing 1,807 consecutive patients in 10 retrospective or prospective nonrandomized studies, 621 (34.4%) of whom were sedated. One case-control study was excluded from prevalence analysis. The most frequent reason for sedation was delirium in the terminal stages of illness (median, 57.1%; range, 13.8% to 91.3%). Benzodiazepines were the most common drug category prescribed. Comparing survival of sedated and nonsedated patients, the sedation approach was not shown to be associated with worse survival. Conclusion: Even if there is no direct evidence from randomized clinical trials, palliative sedation, when appropriately indicated and correctly used to relieve unbearable suffering, does not seem to have any detrimental effect on survival of patients with terminal cancer. In this setting, palliative sedation is a medical intervention that must be considered as part of a continuum of palliative care.

Background: Palliative sedation therapy (PST) is indicated for and used to control refractory symptoms in cancer patients undergoing palliative care. We aimed to evaluate whether PST has a detrimental effect on survival in terminally ill patients. Methods: This multicenter, observational, prospective, nonrandomized population-based study evaluated overall survival in two cohorts of hospice patients, one submitted to palliative sedation (A) and the other managed as per routine hospice practice (B). Cohorts were matched for age class, gender, reason for hospice admission, and Karnofsky performance status. Results: Of the 518 patients enrolled, 267 formed cohort A and 251 cohort B. In total, 25.1% of patients admitted to the participating hospices received PST. Mean and median duration of sedation was 4 (standard deviation 6.0) and 2 days (range 0–43), respectively. Median survival of arm A was 12 days [90% confidence interval (CI) 10–14], while that of arm B was 9 days (90% CI 8–10) (log rank = 0.95, P = 0.330) (unadjusted hazard ratio = 0.92, 90% CI 0.80–1.06). Conclusion: PST does not shorten life when used to relieve refractory symptoms and does not need the doctrine of double effect to justify its use from an ethical point of view.