Misclassification of primary liver cancer in the Life Span Study of atomic bomb survivors

The scientific basis for the use of the linear no-threshold (LNT) model at low doses and dose rates in radiological protection

The linear no-threshold (LNT) model was introduced into the radiological protection system about 60 years ago, but this model and its use in radiation protection are still debated today. This article presents an overview of results on effects of exposure to low linear-energy-transfer radiation in radiobiology and epidemiology accumulated over the last decade and discusses their impact on the use of the LNT model in the assessment of radiation-related cancer risks at low doses. The knowledge acquired over the past 10 years, both in radiobiology and epidemiology, has reinforced scientific knowledge about cancer risks at low doses. In radiobiology, although certain mechanisms do not support linearity, the early stages of carcinogenesis comprised of mutational events, which are assumed to play a key role in carcinogenesis, show linear responses to doses from as low as 10 mGy. The impact of non-mutational mechanisms on the risk of radiation-related cancer at low doses is currently difficult to assess. In epidemiology, the results show excess cancer risks at dose levels of 100 mGy or less. While some recent results indicate non-linear dose relationships for some cancers, overall, the LNT model does not substantially overestimate the risks at low doses. Recent results, in radiobiology or in epidemiology, suggest that a dose threshold, if any, could not be greater than a few tens of mGy. The scientific knowledge currently available does not contradict the use of the LNT model for the assessment of radiation-related cancer risks within the radiological protection system, and no other dose-risk relationship seems more appropriate for radiological protection purposes.

Provider reported challenges with completing death certificates: A focus group study demonstrating potential sources of error

OBJECTIVES

To characterize the experiences of providers in completing the cause of death section on death certificates, with particular reference to deaths in people who have cancer.

METHODS

Focus groups were conducted until thematic saturation was reached, resulting in four groups over three months. Participants were from a variety of specialties and levels and types of training. Focus groups were recorded and transcribed verbatim and analyzed using constant comparison analysis.

RESULTS

Three types of challenges to case classification were identified. 1) Infrastructural and procedural challenges encountered when completing death certificates, including the rigid structure of the form, lack of training in its completion, and lack of real-time feedback. 2) Clinical uncertainty and the varied approaches providers take to determine the cause of death based on their perception of the purpose of the death certificate. 3) Choosing cause of death in decedents with a history of cancer.

CONCLUSIONS

There are specific and substantial challenges in the death certification process that lead to errors in documenting the cause of death, but many of these challenges could be addressed with structural change to the forms or mechanism of training. Using these data to inform change could improve the death certification process and reliability of this data.