Dear editor: Lung cancer (LC) is the number one cause of death among all cancers worldwide¹1. Stewart BW, Kleihues P (eds). World Cancer Report 2014. Lyon: IARC Press, 2003. and in Mexico.²2. Instituto Nacional de Estadística y Geografía. Principales causas de mortalidad por residencia habitual, grupos de edad y sexo del fallecido [internet site]. México: INEGI, 2016 [cited 2017 April 19]. Available from:http://www.inegi.org.mx/est/contenidos/proyectos/registros/vitales/mortalidad/tabulados/PC.asp?t=14&c=11817
http://www.inegi.org.mx/est/contenidos/p... LC mortality rates in Mexico increased for both sexes between 1970 and 1999,³3. Malvezzi M, Bosetti C, Chatenoud L, Rodríguez T, Levi F, Negri E, La Vecchia C. Trends in cancer mortality in Mexico, 1970-1999. Ann Oncol. 2004;15(11):1712-8. https://doi.org/10.1093/annonc/mdh424
https://doi.org/10.1093/annonc/mdh424... but recent studies have shown a favorable decreasing trend.⁴4. Tovar-Guzmán VJ, López-Antuñano FJ, Rodríguez-Salgado N. Trends in mortality from lung cancer in Mexico, 1980-2000. Rev Panam Salud Publica. 2005;17(4):254-62. https://doi.org/10.1590/S1020-49892005000400006
https://doi.org/10.1590/S1020-4989200500... ^,55. Gómez-Dantés H, Lamadrid-Figueroa H, Cahuana-Hurtado L, Silverman-Retana O, Montero P, González-Robledo MC, et al. The burden of cancer in Mexico, 1990-2013. Salud Publica Mex. 2016;58(2):118-31. https://doi.org/10.21149/spm.v58i2.7780
https://doi.org/10.21149/spm.v58i2.7780... However, these studies included all ages in the analysis, or specific age groups (30-74, 35-64, 0-80 years of age), resulting in variable mortality rates. Considering that the majority of malignant lung neoplasms (97%) are usually seen in those age ≥40 years it would be more accurate to determine mortality rates in this population. In this letter we compare the age-standardized mortality rates (ASMR) of LC in people of all ages (ASMR-all) vs people age ≥40 years (ASMR≥40), to determine the degree of underestimation if all ages are considered; compare medians of ASMR≥40 for the periods before and after 2008, when new tobacco taxes and laws were implemented in Mexico, to determine their impact on LC mortality, and determine trends of age-specific rates and of ASMR for the period 1999-2014.

De-identified LC mortality and population growth data were obtained from official websites.⁶6. Secretaría de Salud. Dirección General de Información en Salud. Bases de datos sobre defunciones [internet site]. México: Secretaría de Salud, 2016 [cited 2017 April 19]. Available from:Available from: http://www.dgis.salud.gob.mx/contenidos/basesdedatos/std_defunciones_gobmx.html
http://www.dgis.salud.gob.mx/contenidos/... ^,77. Consejo Nacional de Población. Proyecciones de la población 2010-2050. Datos de Proyecciones [internet site]. México: CONAPO, 2017 [cited 2017 April 19]. Available from: Available from: http://www.conapo.gob.mx/es/CONAPO/Proyecciones_Datos
http://www.conapo.gob.mx/es/CONAPO/Proye... ASMR were calculated according to the World Standard Population⁸8. National Cancer Institute. World (WHO 2000-2025) Standard [internet site]. NCI; 2013 [cited 2017 April 19]. Available from:http://seer.cancer.gov/stdpopulations/world.who.html
http://seer.cancer.gov/stdpopulations/wo... and joinpoint regression analysis⁹9. National Cancer Institute. Joinpoint Trend Analysis Software [internet sited] 2016 [cited 2016 April 19]. Available from:https://surveillance.cancer.gov/joinpoint
https://surveillance.cancer.gov/joinpoin... was used to determine national rate trends. Lung cancer deaths were identified as ICD-10th codes C33 and C34.

The results showed that ASMR≥40 were about three times higher than ASMR-all (table I). Compared to the first period (before 2008), the ASMR≥40 medians of the second period (after 2008) decreased from 26.6 to 20.5 overall, from 15.8 to 13.6 in females and from 38.7 to 28.3 in males. All changes were statistically significant (p<0.001, data not shown). From 1999 to 2014, the annual percent change (APC) of age-specific rates decreased for the whole sample, for females and for males (table II). The largest decline was seen in males aged 65-69, from 2004 to 2008 (APC -8.0). From 1999 to 2014, the ASMR≥40 decreased 36% in the whole sample, 25.6% in females and 39.8% in males, with an APC of -3.0, -2.1 and -3.3, respectively (p<0.05). Higher APC from 2008 to 2014 were found in the whole sample (-3.4) and in males (-4.0) (figure 1, tables I and II). This study shows that LC’s ASMR will be underestimated about threefold if all ages are considered in the analysis. Trend analysis showed a persistent favorable trend in LC mortality in Mexico, which is likely associated with the implementation of smoking laws and taxes in 2008, and the decrease over time of the prevalence of smoking¹⁰10. Kuri-Morales PA, González-Roldán JF, Hoy MJ, Cortés-Ramírez M. Epidemiology of tobacco use in Mexico. Salud Publica Mex . 2006;48(Suppl 1):S91-8. https://doi.org/10.1590/S0036-36342006000700011
https://doi.org/10.1590/S0036-3634200600... ^,1111. Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz. Encuesta Nacional de Adicciones: Reporte de Tabaco. Ciudad de México: INPRFM, 2012. Available from:http://www.conadic.salud. gob.mx/pdfs/ENA_2011_TABACO.pdf
http://www.conadic.salud. gob.mx/pdfs/EN... and of the use of wood as the main cooking fuel.¹²12. Hernández-Garduño E, Gómez-García E, Campos-Gómez S. Prevalence trends of wood use as the main cooking fuel in Mexico, 1990-2013. Salud Publica Mex . 2017;59(1):68-75. https://doi.org/10.21149/7770
https://doi.org/10.21149/7770... Prevalence of biomass smoke exposure (BSE) resulting from cooking is still high in rural areas of Mexico (44.5% in 2012-201312) and has been associated with lung cancer in Mexican women,¹³13. Hernández-Garduño E, Brauer M, Pérez-Neria J, Vedal S. Wood smoke exposure and lung adenocarcinoma in non-smoking Mexican women. Int J Tuberc Lung Dis. 2004;8:377-83. who usually perform the cooking. BSE may be contributing to the slower pace of decrease in ASMR in women, as they have a lower smoking prevalence than men.

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