On 2015 Jan 09, William Grant commented:

Low UVB exposure accounts for some of the increased risk of cancer for waiters in Nordic countries

The paper by Reijula and colleagues investigated the risk of cancer for waiters in the five Nordic countries for the period 1961 to 2005 [1]. They found that all-cancer incidence rates were 46% (95% CI, 41%-51%) higher for men and 9% (7%-11%) higher for women. They attributed much of the difference to higher alcohol consumption, smoking, and occupational exposure to tobacco smoke. Overlooked in their paper was any discussion of the role of solar UVB and vitamin D in affecting risk of cancer.

I used data in their related paper from 2009 [2] to estimate the effect of UVB in reducing risk of cancer in the Nordic countries. I reasoned that those in the 54 occupational categories had different UVB exposures depending on how much working time they spent out of doors. The index I developed was lip cancer incidence less lung cancer incidence for males (females wear lipstick, so do not develop much lip cancer) [3]. As they noted, "All eight occupations with significant SIRs (standardized incidence rates) [for lip cancer] >1.20 in males include a major part of outdoor work, while the lowest SIRs are in indoor occupations." However, smoking is also a risk factor for lip cancer, hence the combined cancer incidence index. Men in the occupations with the greatest time spent out of doors had the lowest rates of most types of cancer.

Looking at the findings for waiters in Ref. 1, both male and female waiters have significantly increased incidence rates for many of the UVB/vitamin D-sensitive cancers [3, 4], although as mentioned in Ref. 1, the largest SIRs are for the smoking-related types of cancer. They also had lower rates of melanoma and the women had lower rates of non-melanoma skin cancer, indicating that they spent less time in the sun than those in other professions. Thus, waiters and others in Nordic countries whose occupations keep them largely indoors could reduce their risk of cancer by spending more time out of doors when the UVB intensity is high enough to make vitamin D [5] or taking vitamin D supplements to raise 25-hydroxyvitamin D concentrations to at least 75-100 nmol/L [6].

References 1. Reijula J, Kjaerheim K, Lynge E, et al. Cancer incidence among waiters: 45 years of follow-up in five Nordic countries. Scand J Public Health. 2015 Jan 6. pii: 1403494814565130. [Epub ahead of print] 2. Pukkala E, Martinsen JI, Lynge E, et al. Occupation and cancer - follow-up of 15 million people in five Nordic countries. Acta Oncol. 2009;48(5):646-790. 3. Grant WB. Role of solar UV irradiance and smoking in cancer as inferred from cancer incidence rates by occupation in Nordic countries. Dermatoendocrinol. 2012;4(2):203-11. 4. Moukayed M and Grant WB. Molecular link between vitamin D and cancer prevention. Nutrients. 2013;5(10):3993-4023. 5. Engelsen O. The relationship between ultraviolet radiation exposure and vitamin D status. Nutrients. 2010;2(5):482-95. 6. Garland CF, French CB, Baggerly LL, Heaney RP. Vitamin D supplement doses and serum 25-hydroxyvitamin D in the range associated with cancer prevention. Anticancer Res 2011;31:617-22.

Disclosure I receive funding from Bio-Tech Pharmacal (Fayetteville, AR) and MediSun Technology (Highland Park, IL).

On 2015 Jan 09, William Grant commented:

Low UVB exposure accounts for some of the increased risk of cancer for waiters in Nordic countries

The paper by Reijula and colleagues investigated the risk of cancer for waiters in the five Nordic countries for the period 1961 to 2005 [1]. They found that all-cancer incidence rates were 46% (95% CI, 41%-51%) higher for men and 9% (7%-11%) higher for women. They attributed much of the difference to higher alcohol consumption, smoking, and occupational exposure to tobacco smoke. Overlooked in their paper was any discussion of the role of solar UVB and vitamin D in affecting risk of cancer.

I used data in their related paper from 2009 [2] to estimate the effect of UVB in reducing risk of cancer in the Nordic countries. I reasoned that those in the 54 occupational categories had different UVB exposures depending on how much working time they spent out of doors. The index I developed was lip cancer incidence less lung cancer incidence for males (females wear lipstick, so do not develop much lip cancer) [3]. As they noted, "All eight occupations with significant SIRs (standardized incidence rates) [for lip cancer] >1.20 in males include a major part of outdoor work, while the lowest SIRs are in indoor occupations." However, smoking is also a risk factor for lip cancer, hence the combined cancer incidence index. Men in the occupations with the greatest time spent out of doors had the lowest rates of most types of cancer.

Looking at the findings for waiters in Ref. 1, both male and female waiters have significantly increased incidence rates for many of the UVB/vitamin D-sensitive cancers [3, 4], although as mentioned in Ref. 1, the largest SIRs are for the smoking-related types of cancer. They also had lower rates of melanoma and the women had lower rates of non-melanoma skin cancer, indicating that they spent less time in the sun than those in other professions. Thus, waiters and others in Nordic countries whose occupations keep them largely indoors could reduce their risk of cancer by spending more time out of doors when the UVB intensity is high enough to make vitamin D [5] or taking vitamin D supplements to raise 25-hydroxyvitamin D concentrations to at least 75-100 nmol/L [6].

References 1. Reijula J, Kjaerheim K, Lynge E, et al. Cancer incidence among waiters: 45 years of follow-up in five Nordic countries. Scand J Public Health. 2015 Jan 6. pii: 1403494814565130. [Epub ahead of print] 2. Pukkala E, Martinsen JI, Lynge E, et al. Occupation and cancer - follow-up of 15 million people in five Nordic countries. Acta Oncol. 2009;48(5):646-790. 3. Grant WB. Role of solar UV irradiance and smoking in cancer as inferred from cancer incidence rates by occupation in Nordic countries. Dermatoendocrinol. 2012;4(2):203-11. 4. Moukayed M and Grant WB. Molecular link between vitamin D and cancer prevention. Nutrients. 2013;5(10):3993-4023. 5. Engelsen O. The relationship between ultraviolet radiation exposure and vitamin D status. Nutrients. 2010;2(5):482-95. 6. Garland CF, French CB, Baggerly LL, Heaney RP. Vitamin D supplement doses and serum 25-hydroxyvitamin D in the range associated with cancer prevention. Anticancer Res 2011;31:617-22.

Disclosure I receive funding from Bio-Tech Pharmacal (Fayetteville, AR) and MediSun Technology (Highland Park, IL).