Laryngeal Cancer

Background

What is laryngeal cancer?

Laryngeal cancer is a relatively rare cancer. The Canadian Cancer Society estimates there will be 1150 new cases in 2020 (1). It is more common in men than in women. Smoking and drinking alcohol are the most important non-occupational risk factors for laryngeal cancer.

 

Known occupational risk factors
    • Asbestos
    • Strong inorganic acid mists (e.g. sulfuric acid)
Possible occupational risk factors
    • Second-hand smoking
    • Rubber production industry
    • Sulfur mustard (mustard gas)
Key Findings

Construction

Workers in the construction industry overall, as well as some specific trades, have an increased risk of laryngeal cancer. Construction workers may be exposed to many different known and suspected carcinogens including asbestos, which is a known risk factor for laryngeal cancer. Construction workers may also be exposed to second-hand smoke in the workplace, which is a possible risk factor for laryngeal cancer.

    • Construction industry: 1.2 times the risk

    • Excavating, grading, paving and related: 1.9 times the risk

    • Plasterers and related: 1.3 times the risk

    • Roofing, waterproofing and related: 1.7 times the risk

    • Structural metal erectors: 1.4 times the risk

    • Glaziers: 1.7 times the risk

    • Occupations in labouring and other elemental work, other construction trades: 1.4 times the risk

Mining and metal processing

It is unclear why workers in the metal mining industry and metal processing have an increased risk of laryngeal cancer.

    • Metal mines: 1.3 times the risk

    • Mining and quarrying: cutting, handling, and loading occupations: 1.8 times the risk

    • Labouring and other elemental work in metal processing: 2.3 times the risk

    • Metal processing and related occupations: 2.2 times the risk

Cleaners

Janitors and cleaners are exposed to dust and various chemical solvents, and possibly asbestos, which may increase the risk of laryngeal cancer.

    • Janitors, charworkers and cleaners: 1.3 times the risk

Relative Risk by Industry and Occupation

Figure 1. Risk of laryngeal cancer diagnosis among workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016

The hazard ratio is an estimate of the average time to diagnosis among workers in each industry/occupation group divided by that in all others during the study period. Hazard ratios above 1.00 indicate a greater risk of disease in a given group compared to all others. Estimates are adjusted for birth year and sex. The width of the 95% Confidence Interval (CI) is based on the number of cases in each group (more cases narrows the interval).

 

Figure 2. Risk of laryngeal cancer diagnosis among workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016 

The hazard ratio is an estimate of the average time to diagnosis among workers in each industry/occupation group divided by that in all others during the study period. Hazard ratios above 1.00 indicate a greater risk of disease in a given group compared to all others. Estimates are adjusted for birth year and sex. The width of the 95% Confidence Interval (CI) is based on the number of cases in each group (more cases narrows the interval).

Table of Results

Table 1. Surveillance of Laryngeal Cancer: Number of cases, workers employed, and hazard ratios in each industry (SIC)

SIC Code * Industry Group Number of cases Number of workers employed Hazard Ratio
(95% CI) †
1 Agriculture 38 35,014 1.21
(0.88-1.66)
2/3 Forestry, Fishing and
Trapping
28 10,699 1.55
(1.07-2.25)
4 Mines, Quarries and
Oil Wells
71 23,200 1.43
(1.13-1.81)
5 Manufacturing 949 693,585 1.01
(0.93-1.09)
6 Construction 332 210,974 1.19
(1.06-1.34)
7 Transportation, Communication
and Other Utilities
313 197,212 1.24
(1.10-1.39)
8 Trade 373 429,290 1.00
(0.90-1.12)
9 Finance, Insurance and
Real Estate
43 23,988 1.46
(1.08-1.98)
10 Community, Business and
Personal Service
368 599,658 0.92
(0.82-1.03)
11 Public Administration and
Defense
240 190,897 1.01
(0.88-1.15)
         
* SIC: Standard Industrial Classification (1970)
† Hazard rate in each group relative to all others

 

Table 2. Surveillance of Laryngeal Cancer: Number of cases, workers employed, and hazard ratios in each occupation (CCDO) group

CCDO Code * Occupation Group Number of cases Number of workers employed Hazard Ratio
(95% CI) †
11 Managerial, administrative
and related
19 31,004 0.77
(0.49-1.21)
21 Natural sciences, engineering
and mathematics
26 26,349 0.87
(0.59-1.29)
23 Social sciences and
related fields
18 30,715 1.66
(1.04-2.64)
25 Religion 0 128
27 Teaching and related 12 48,491 0.47
(0.27-0.84)
31 Medicine and health 40 135,372 0.74
(0.54-1.02)
33 Artistic, literary,
recreational and related
6 14,996 0.65
(0.29-1.44)
41 Clerical and related 137 197,348 0.88
(0.74-1.04)
51 Sales 67 148,140 0.78
(0.61-0.99)
61 Service 315 370,912 1.01
(0.90-1.14)
71 Farming, horticultural
and animal husbandry
47 50,150 1.02
(0.76-1.36)
73 Fishing, hunting,
trapping and related
<5 558
75 Forestry and logging 22 10,684 1.27
(0.84-1.94)
77 Mining and quarrying,
including oil and gas field
35 13,036 1.28
(0.92-1.79)
81 Processing
(mineral, metal, chemical)
126 79,239 1.36
(1.13-1.62)
82 Processing
(food, wood, textile)
80 99,250 0.78
(0.62-0.97)
83 Machining and related 295 189,415 1.08
(0.96-1.23)
85 Product fabricating,
assembling and repairing
458 328,320 1.04
(0.94-1.15)
87 Construction trades 377 215,593 1.16
(1.04-1.30)
91 Transport equipment
operating
343 168,109 1.52
(1.35-1.70)
93 Materials handling and related,
not elsewhere classified
205 153,057 1.23
(1.07-1.42)
95 Other crafts and
equipment operating
46 28,305 1.19
(0.89-1.59)
99 Other occupations not elsewhere classified 255 215,261 1.04
(0.92-1.19)
         
* CCDO: Canadian Classification Dictionary of Occupations (1971)
† Hazard rate in each group relative to all others

Please note that ODSS results shown here may differ from those previously published or presented. This may occur due to changes in case definitions, methodological approaches, and the ongoing nature of the surveillance cohort.

References

  1. Brenner DR, Weir HK, Demers AA, Ellison LF, Louzado C, Shaw A, Turner D, Woods RR, Smith LM. Projected estimates of cancer in Canada in 2020. CMAJ 2020;192:E199-205.