Incidence, Trends and Ethnic Differences of Oropharyngeal, Anal and Cervical Cancers: Singapore, 1968-2012

Abstract

In recent decades, several Western countries have reported an increase in oropharyngeal and anal cancers caused by human papillomavirus (HPV). Trends in HPV-associated cancers in Asia have not been as well described. We describe the epidemiology of potentially HPV-related cancers reported to the Singapore Cancer Registry from 1968-2012. Analysis included 998 oropharyngeal squamous cell carcinoma (OPSCC), 183 anal squamous cell carcinoma (ASCC) and 8,019 invasive cervical cancer (ICC) cases. Additionally, 368 anal non-squamous cell carcinoma (ANSCC) and 2,018 non-oropharyngeal head and neck carcinoma (non-OP HNC) cases were included as comparators. Age-standardized incidence rates (ASR) were determined by gender and ethnicity (Chinese, Malay and Indian). Joinpoint regression was used to evaluate annual percentage change (APC) in incidence. OPSCC incidence increased in both genders (men 1993-2012, APC = 1.9%, p<0.001; women 1968-2012, APC = 2.0%, p = 0.01) and was 5 times higher in men than women. In contrast, non-OP HNC incidence declined between 1968-2012 among men (APC = -1.6%, p<0.001) and women (APC = -0.4%, p = 0.06). ASCC and ANSCC were rare (ASR = 0.2 and 0.7 per 100,000 person-years, respectively) and did not change significantly over time except for increasing ANSCCs in men (APC = 2.8%, p<0.001). ICC was the most common HPV-associated cancer (ASR = 19.9 per 100,000 person-years) but declined significantly between 1968-2012 (APC = -2.4%). Incidence of each cancer varied across ethnicities. Similar to trends in Western countries, OPSCC incidence increased in recent years, while non-OP HNC decreased. ICC remains the most common HPV-related cancer in Singapore, but Pap screening programs have led to consistently decreasing incidence.

Fig 1. Incidence of oropharyngeal and non-oropharyngeal head and neck squamous cell carcinomas in Singapore 1968–2012, by gender.

Incidence trends are based on incidence rates for 5-year time periods that were age-adjusted to the WHO standard population. Annual percent change (APC) was calculated using Joinpoint regression analysis. APC = annual percent change. An asterisk (*) indicates an APC value that is statistically significant at p≤0.05. Abbreviations: OPSCC = oropharyngeal squamous cell carcinoma; non-OP HNC = non-oropharyngeal head and neck squamous cell carcinoma

Fig 2. Incidence of invasive anal cancer in Singapore, 1968–2012, by gender and histology.

Incidence trends are based on incidence rates for 5-year time periods that were age-adjusted to the WHO standard population. Annual percent change (APC) was calculated using Joinpoint regression analysis. APC = annual percent change. An asterisk (*) indicates an APC value that is statistically significant at p≤0.05. Abbreviations: SCC = squamous cell carcinoma, non-SCC = non-squamous cell carcinoma

Fig 3. Incidence of invasive cervical cancer in Singapore, 1968–2012, by ethnicity.

Incidence trends are based on incidence rates for 5-year time periods that were age-adjusted to the WHO standard population. Annual percent change (APC) was calculated using Joinpoint regression analysis. APC = annual percent change. An asterisk (*) indicates an APC value that is statistically significant at p≤0.05.