Purpose Treatment-related stomach cancer is an important cause of morbidity and mortality among the growing number of Hodgkin lymphoma (HL) survivors, but risks associated with specific HL treatments are unclear.

A 15-Country collaborative cohort study was conducted to provide direct estimates of cancer risk following protracted low doses of ionizing radiation. Analyses included 407,391 nuclear industry workers monitored individually for external radiation and 5.2 million person-years of follow-up. A significant association was seen between radiation dose and all-cause mortality [excess relative risk (ERR) 0.42 per Sv, 90% CI 0.07, 0.79; 18,993 deaths]. This was mainly attributable to a dose-related increase in all cancer mortality (ERR/Sv 0.97, 90% CI 0.28, 1.77; 5233 deaths). Among 31 specific types of malignancies studied, a significant association was found for lung cancer (ERR/Sv 1.86, 90% CI 0.49, 3.63; 1457 deaths) and a borderline significant (P = 0.06) association for multiple myeloma (ERR/Sv 6.15, 90% CI <0, 20.6; 83 deaths) and ill-defined and secondary cancers (ERR/Sv 1.96, 90% CI -0.26, 5.90; 328 deaths). Stratification on duration of employment had a large effect on the ERR/Sv, reflecting a strong healthy worker survivor effect in these cohorts. This is the largest analytical epidemiological study of the effects of low-dose protracted exposures to ionizing radiation to date. Further studies will be important to better assess the role of tobacco and other occupational exposures in our risk estimates.

Objectives To provide direct estimates of risk of cancer after protracted low doses of ionising radiation and to strengthen the scientific basis of radiation protection standards for environmental, occupational, and medical diagnostic exposures.Design Multinational retrospective cohort study of cancer mortality.Setting Cohorts of workers in the nuclear industry in 15 countries.Participants 407 391 workers individually monitored for external radiation with a total follow-up of 5.2 million person years.Main outcome measurements Estimates of excess relative risks per sievert (Sv) of radiation dose for mortality from cancers other than leukaemia and from leukaemia excluding chronic lymphocytic leukaemia, the main causes of death considered by radiation protection authorities.Results The excess relative risk for cancers other than leukaemia was 0.97 per Sv, 95% confidence interval 0.14 to 1.97. Analyses of causes of death related or unrelated to smoking indicate that, although confounding by smoking may be present, it is unlikely to explain all of this increased risk. The excess relative risk for leukaemia excluding chronic lymphocytic leukaemia was 1.93 per Sv (< 0 to 8.47). On the basis of these estimates, 1-2% of deaths from cancer among workers in this cohort may be attributable to radiation.Conclusions These estimates, from the largest study of nuclear workers ever conducted, are higher than, but statistically compatible with, the risk estimates used for current radiation protection standards. The results suggest that there is a small excess risk of cancer, even at the low doses and dose rates typically received by nuclear workers in this study.

of having both a minimum latency of 17 years (compared with the 10-year lag of Gilbert et al.) and a minimum exposure age of 62 years (compared with no exclusions, as in the analysis of Gilbert et al.). This table also shows that the trend statistic (3.90) was much higher than the value of Gilbert et al. for Hanford workers (2.19). In the summary of their paper Gilbert and her associates are inclined to attribute their significant findings for high death ages to biases in the data that are not well understood. Therefore, it is interesting to consider what might have been the effects of faulty recording of cancer deaths and/or faulty recording of radiation doses. Faults of both kinds were possible, and the first would only require doctors who knew of the nuclear industry connection to be repeatedly overrecording cancer as the cause of death of workers who combined high doses with high death ages. However, when we added to the other controlling factors the age on leaving the industry, we found that for exposures after 60 years of age, with a lag period of 15 years (i.e. 75 years as the minimum age for a radiogenic cancer death), the trend statistic (3.51) was still much higher than the value of Gilbert et al. Therefore, faulty recording of cancer deaths could have been the cause of the suspected bias only if it had distinguished between workers with low and high doses who had in common both the age when they left the industry and the age when they died. Finally, although faulty recording of radiation doses was possible, it is difficult to see how this could have effects which were less obvious for deaths within 10 years of leaving the industry than for deaths with longer post-employment intervals.

The incidence of symptomatic CNS leukemia was studied in 209 children, all of whom were entered in a cooperative study during 1963‐1964, and received the same chemotherapeutic agents. The overall incidence was 51%, and the median time for occurrence of the first episode was 9 months. The incidence was 56% in patients with acute lymphocytic leukemia (A. L. L.) and 25% in those with other forms of leukemia. CNS symptoms developed at a steady monthly rate of 3.8% for the first 24 months and then decreased to 2%. The rate for the first year was the same for all forms of leukemia; it was 4% in A. L. L. and 3.7% in the other forms combined. The overall median survival was 18 months—it was 21 months for patients with A. L. L. and 9 months for the other cell types. Life‐table analysis showed a median survival of 8 months for patients who had developed CNS leukemia and 24 months for those free of the complication. Age, sex, hematologic status, and chemotherapy regimen did not influence the incidence. We conclude that the increasing survival of children with leukemia is the chief cause for the increased incidence of CNS leukemia noted by many investigators.

In a group of 1770 children with acute leukemia, treated in 11 pediatric centers associated with Children's Cancer Group A, surgical data was related to age at diagnosis, morphological type, the leukocyte count at onset, and the year of diagnosis. The age distribution was different in the 3 morphological types of childhood leukemia. A peak at the age 2 to 3 years, with a broad base extending from 2 to 5 years, was characteristic of acute lymphoid leukemia, while the peak was absent in other morphological types. The age distribution was similar in Caucasian and Negro children. The most favorable prognosis was found in children with acute lymphoid leukemia who were 2 to 6 years of age at diagnosis in whom the leukocyte counts were below 4,000/mm3 at onset. Progress in extending the median survival time of all children with acute lymphoid but not other types of leukemia was noted between 1957 and 1964. The 10% survival figure improved for all types of leukemia during this period.

The use of a linear function for discriminating with dichotomous variables is discussed and evaluated. Four such functions are considered: Fisher's linear discriminant function, two functions based upon a logistic model, and a function based upon the assumption of mutual independence of the variables. The evaluation of these functions as well as of a completely general multinomial procedure is carried out within the context of a 1st order interaction model by means of computer experiments. The product moment correlation of the optimal function with the linear function under evaluation plays a central role as a criterion for judging the relative merits of the procedures considered.