Induction of Human Squamous Cell-Type Carcinomas by Arsenic

Table 1

Studies exhibiting associations between arsenic exposition and cell types of lung cancer.

Location	Number of lung cancer cases	Cell type	Smoking status	Calculated risk	Dosage	Reference
Britain	6 cases treated with Fowler’s solution or potassium arsenite (2 male/4 female)	(i) 5 undifferentiated carcinomas; (ii) 1 SqCC	3 never smokers, 1 smoker	NA	NA	[94]
Taiwan	(i) 76 LC cases (50 males/36 females); (ii) 400 controls from the same administrative area	(i) Male cases: 40% SqCC, 38% AdC, 22% others; (ii) Female cases: 19% SqCC, 69% AdC, 11% others	NA	Odds ratios for developing LC were 3.39 for whom used well water from arsenic-contaminated zones during 40 or more years,; compared with people who never used such water source	Median of 780 μg/L (artesian wells) and 40 μg/L (in well water)	[95]
Japan: Niigata Prefecture	(i) 443 individuals exposed to arsenic; (ii) 9 (8 male/1female); developed lung cancer after exposure to high levels (≥1000 μg/L)	(i) 3 SCC; (ii) 2 SqCC; (iii) 1 SqCC + SCC	All smokers, except for female case	SMR=15.6 for developing LC among individuals (𝑁=113) exposed to >1000 μg/L of arsenic in drinking water in a zone contaminated during 5 years in Japan, while individuals exposed to 50−990 μg/L (𝑁=76) present a SMR of 2.33		[96]
Southwest and northeast Taiwan	139 newly diagnosed LC cases from a BFD endemic zone	(i) 45% SqCC; (ii) 22% AdC	(i) 31.9% never smokers; (ii) 16.7% past smokers; (iii) 51.4% current smokers	Relative risk according to exposure group; (i) Group 1: 1; (ii) Group 2: 1.09; (iii) Group 3: 2.28; (iv) Group 4: 3.03; (v) Group 5: 3.29	Average arsenic level in groundwater (μg/L); (i) Group 1: <10; (ii) Group 2: 10–99l; (iii) Group 3: 100–299l; (iv) Group 4: 300–699; (v) Group 5:≥700	[97]
Taiwan	National Cancer Registration Program with 37.290 LC patients (26.850 men/10.440 women	Men^†; (i) 33.6% SqCC; (ii) 19.5% AdC; Women^†; (i) 29.9% SqCC; (ii) 29.6% SqCC	NA	Male and female patients from; the BFD area had higher proportions of SqCC; (RR=1.1 in men and RR=1.9 in women) and SCC (RR=1.2, in men, and RR=2.3, in women) but had a lower proportion of AdC; (RR=0.7 in men and RR=0.6in women)	(i) Towns in BFD; area: average arsenic level of 0.22 mg/L in well water; (ii) Control towns: average arsenic; level of 0.02 mg/L	[40]
Bangladesh	(i) 3.223 (2811 male) with a primary LC; (ii) 1588 (1183 male) with benign lesions	50.5% and 39.0% of SqCC among smokers and nonsmokers, respectively	(i) 79.7% smokers; (ii) 18.5% never; (iii) 1.80% unknown	OR = 1.45,; (95% CI 1.16−1.80)	>100 μg/L	[63]
Northeastern Taiwan	(i) 8086 residents were followed for 11 years (6888 remained in the final analysis); (ii) 178 incident LC cases	(i) 75 (42.1%) SqCC; (ii) 51 (28.7%) AdC; (iii) 22 (12.4%) SCC	At enrollment; (i) 59.0% never smokers; (ii) 12.4% past; (iii) 28.6% current	The RRs and 95% CIs for 100–300 and >300 μg arsenic/L when compared with <10 μg arsenic/L were 1.54 (0.97–2.46) and 2.25 (1.43–3.55), respectively	The mean (arsenic) among wells with known arsenic concentration was 117.2 μg/L	[98]
USA: New Hampshire, Vermont.	(i) 223 lung cancer (100 male/123 female); (ii) 238 controls	75 cases were SqCC and SCC	Data from cases; (i) 5.4% never smokers; (ii) 94.6% current	Arsenic exposure was associated with SCC and SqCC (OR =2.75 for toenail arsenic concentration ≥0.114 μg/g versus <0.05 μg/g)	Toe nail (arsenic) in 4 levels: <0.05 μg/g, 0.05 to<0.0768 μg/g, 0.768; to <0.1137 μg/g, and ≥0.1137 μg/g	[99]

^†Data from patients from the Blackfoot Disease area in Taiwan.
SCC: small cell carcinoma; NA: data not available; SMR: standardized mortality rate; OR: odds ratios.