Occupation and Risk of Non-hodgkin Lymphoma and Its Subtypes

A Pooled Analysis From the InterLymph Consortium

Andrea 't Mannetje; Anneclaire J. De Roos; Paolo Boffetta; Roel Vermeulen; Geza Benke; Lin Fritschi; Paul Brennan; Lenka Foretova; Marc Maynadié; Nikolaus Becker; Alexandra Nieters; Anthony Staines; Marcello Campagna; Brian Chiu; Jacqueline Clavel; Silvia de Sanjose; Patricia Hartge; Elizabeth A. Holly; Paige Bracci; Martha S. Linet; Alain Monnereau; Laurent Orsi; Mark P. Purdue; Nathaniel Rothman; Qing Lan; Eleanor Kane; Adele Seniori Costantini; Lucia Miligi; John J. Spinelli; Tongzhang Zheng; Pierluigi Cocco; Anne Kricker

Disclosures

Environ Health Perspect. 2016;124(4):396-405. 

In This Article

Results

The 10 case–control studies included 10,046 cases and 12,025 controls (Table 1). Of the cases, 50% were from Europe, 43% were from North America, and 7% were from Australia. The year of diagnosis ranged from 1988 to 2004, and 52.4% of cases were male. The mean ± standard deviation (SD) age at interview was 57.6 ± 12.8 years for cases and 55.4 ± 14.2 years for controls. The mean year of first employment (in the 8 studies with full occupational history) was 1959 (± 16 years; range, 1915–2003) for cases and 1961 (± 16 years; range, 1912–2002) for controls. Of the four subtypes selected for separate analyses, DLBCL formed the largest group with 3,061 cases (52.4% male), followed by FL (2,140 cases; 45.6% male), CLL/SLL (1,014 cases; 59.3% male), and PTCL (632 cases; 56.5% male).

None of the 24 broad occupational groups of a priori interest (see Table 2) had a statistically significant positive association with NHL for ever employment (Table 3). However, one or more specific titles within 10 of these 24 groups were positively associated with NHL. There were positive associations with ever employment in cleaning occupations for "charworkers, cleaners and related" (OR = 1.17; 95% CI: 1.01, 1.36) and in electrical and electronic occupations for "electrical wiremen" (OR = 1.24; 95% CI: 1.00, 1.54); there were also positive associations with > 10 years employment for "electrical fitters & related electrical/electronics workers" and selected subgroups of these occupations. Among farming occupations, ever employment as "field crop and vegetable farm workers" (OR = 1.26; 95% CI: 1.05, 1.51) and as "general farm workers" (OR = 1.19; 95% CI: 1.03, 1.37) had a positive association with NHL. Employment of > 10 years as a forestry worker was also associated with NHL (OR = 2.25; 95% CI: 1.18, 4.32; 28 cases, 14 controls). Other positive associations were observed for NHL for ever employment as a "women's hairdresser" (OR = 1.34; 95% CI: 1.02, 1.74), among painters as "spray-painters (except construction)" (OR = 2.07; 95% CI: 1.30, 3.29), among textile workers as "milliners and hatmakers" (OR = 2.46; 95% CI: 1.28, 4.74), and among woodworker occupations as "general carpenter" (OR = 1.42; 95% CI: 1.04, 1.93). Furthermore, > 10 years employment was positively associated with NHL among medical workers for "medical doctors" (OR = 1.87; 95% CI: 1.23, 2.85; 57 cases, 38 controls) and among metal workers for "machine-tool operators" (OR = 1.55; 95% CI: 1.11, 2.17; 84 cases; 63 controls). The occupational group of teachers was negatively associated with NHL (OR = 0.89; 95% CI: 0.81, 0.98), as were some of the specific occupations within the teachers group. Only "head teachers" had a positive association with NHL (OR = 2.16; 95% CI: 1.15, 4.06).

Table 4 presents ORs and 95% CIs for the four NHL subtypes for both sexes combined. DLBCL, the most common subtype, had positive associations with the occupational groups of hairdressers (OR = 1.47; 95% CI: 1.08, 2.00; 58 cases, 158 controls) and textile workers (OR = 1.19; 95% CI: 1.01, 1.41; 218 cases, 773 controls) as well as with specific occupations within these groups (women's hairdresser, milliners and hatmakers, and sewers and embroiderers). Positive associations were also observed for specific occupations as "charworkers, cleaners and related workers" (OR = 1.27; 95% CI: 1.03, 1.58; 122 cases, 395 controls), "field crop & vegetable farm workers" (OR = 1.50; 95% CI: 1.15, 1.97; 79 cases, 233 controls) and its subgroup "field crop farm worker (general)" (OR = 1.48; 95% CI: 1.01, 2.17; 38 cases, 118 controls), "metal melters and reheaters" (OR = 2.31; 95% CI: 1.01, 5.26; 10 cases, 14 controls), and "special education teachers" (OR = 1.94; 95% CI: 1.01, 3.71; 14 cases, 24 controls). Forestry workers with > 10 years employment also had a positive association with DLBCL (OR = 3.04, 95% CI: 1.34, 6.90; 10 cases, 14 controls).

Positive associations were present for FL with specific occupations such as "spray-painter (except construction)" (OR = 2.67; 95% CI: 1.36, 5.25; 13 cases, 29 controls) and with > 10 years employment as a "medical doctor" (OR = 2.23, 95% CI: 1.17, 4.26; 13 cases, 38 controls).

CLL/SLL was associated with ever employment in the occupational group of hairdressers (OR = 1.79; 95% CI: 1.06, 3.03; 18 cases, 130 controls), both for the specific occupation "women's hairdresser" as well as for > 10 years employment in the occupational group of hairdressers (OR = 2.09, 95% CI: 1.01, 4.34; 10 cases, 40 controls). We observed positive associations with CLL/SLL for specific occupations such as "general farm worker" (OR = 1.44; 95% CI: 1.13, 1.84; 102 cases, 399 controls), printing pressmen (OR = 6.52; 95% CI: 2.79, 15.21; 10 cases, 19 controls), "pre-primary education teachers" (OR = 2.00; 95% CI: 1.04, 3.87; 11 cases, 111 controls) and carpenters (OR = 2.10; 95% CI: 1.08, 4.09; 13 cases, 69 controls). CLL/SLL was also associated with > 10 years employment as machine tool operators (OR = 1.96; 95% CI: 1.04, 3.69; 15 cases, 46 controls).

Three occupational groups had positive associations with PTCL: ever employment as painters (OR = 1.80; 95% CI: 1.14, 2.84; 22 cases, 221 controls), textile workers (OR = 1.60; 95% CI: 1.18, 2.17; 56 cases, 773 controls), and wood workers (OR = 1.54; 95% CI: 1.04, 2.27; 31 cases, 352 controls); the last two occupational groups also had increased ORs for > 10 years employment. Specific textile occupations associated with PTCL included "spinners, weavers, knitters, dyers and related workers" (OR = 1.85; 95% CI: 1.21, 2.83; 27 cases, 313 controls) and "tailors, dressmakers, sewers, upholsterers and related workers" (> 10 year OR = 2.29, 95% CI: 1.38, 3.77, 19 cases, 183 controls). The specific wood worker occupation associated with PTCL was "cabinet makers" (OR = 2.41; 95% CI: 1.22, 4.74; 10 cases, 81 controls). PTCL was also associated with "electrical fitters" (ever employed OR = 2.02; 95% CI: 1.03, 3.97; 10 cases, 92 controls).

Evidence of heterogeneity in relative risks (p < 0.05, Q-test for heterogeneity) across the four NHL subtypes was present for "women's hairdressers," metal workers, "printing pressmen," textile workers, and "cabinetmakers" (Table 4). "Printing pressmen," however, had very small numbers of cases and controls (< 10) for all analyses except for CLL/SLL.

Attributable Fraction

We estimated the proportion of NHL and of each subtype that was attributable to the main occupational groups (farmers, textile workers, hairdressers, wood workers, painters) or to specific occupations (e.g., "women's hairdressers," "spray-painters") for which an elevated relative risk had been observed (p < 0.05). AFs for NHL were low, between 0.3% for "women's hairdressers" and 0.63% for "general farm workers," and were somewhat higher for the rarer individual subtypes: 1.49% for "women's hairdressers" and CLL/SLL and ≥ 3.69% for the textile worker group and PTCL. AFs differed by sex in a number of occupations, reflecting the scarcity of men or women in a particular occupation.

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