Introduction

Oral cancer (including cancers of the mouth, lip and tongue) is a major
public health problem in certain regions of Europe, Latin America and Asia,
including India1 where it ranks as one of the leading cancer sites
among men and women in many regions2.Major risk factors for oral cancer, are the use of
tobacco, betel quid and alcohol3,4. Despite existing tobacco and alcohol control
policies5,6, mouth cancer incidence has been increasing in most
population-based cancer registries (PBCRs) in India. In a country such as India, where access to
healthcare services and cancer-related awareness is highly variable, changes in
incidence rates should be interpreted carefully. A more in-depth analysis of
important underlying factors related to age, gender and time period for these
trends can yield information for planning rationale cancer control programmes.
We conducted an age period analysis of oral cancer
incidence trends using the PBCR data in Delhi over a 24-year time period (1990–
2014) to address the trends of one of the leading cancer sites in Delhi, and to
better understand the differences by gender and age.

MATERIALS
AND METHODS:

The numbers of cases
cancer of oral cavity were obtained for the period 1990 to 2014 from Delhi
PBCR. Delhi PBCR was established by the Indian Council of Medical Research
(ICMR) in January 1986, at the AIIMS, with the objective of generating reliable
data on the magnitude, trends, and patterns of cancers in Delhi. Delhi PBCR
records cancer cases from more than 180 government and 250 private facilities. The
records are compiled by NCRP of Indian Council of Medical Research (ICMR), and
data are available in public domain.

The data were
segregated by sex, age, and anatomical site based on the World Health
Organisation International Classification of Diseases for Oncology, 3rd edition
(ICDO- 3).We extracted information on all incident cases of cancer of the lip
(C00), tongue (C01–C02) and mouth ICD-O-3-6; gingiva (C03), floor of the
mouth (C04), palate (C05), cheek mucosa, vestibule, retromolar area and other
unspecified parts of the mouth (C06). Subjects were categorised into 5
ten-year age groups (<20, 20–29, 30–39, 40– 49, 50-59 years). Cases above 59 years of age were excluded due to less complete and accurate diagnostic data in older persons (60+ years). Annual mid-year population estimates for the period by age group and sex were obtained from the Census of India data. Raw data were analysed to calculate age specific incidence rates. Incidence analysis was performed through the calculation of age-standardized incidence rates by sex and expressed in cases per 100,000 persons/year. The age-standardized incidence rates were calculated by the direct method for each year, utilizing the world standard population (Segi) as a reference7.     RESULTS: The relative proportion of Oral Cancer among all types of Cancer (Table-1) in Delhi has shown alarming rise from year 2003 onwards. We have observed a steady situation in Oral cancer proportion from year 1990 to 2003. But during last decade the Oral cancer incidence proportion has shown almost 150% increase, thus making Oral cancer the most common type of cancer in Delhi.   Oral Cancer Age-specific incidence rates of oral cancer for different age groups and for both gender populations are presented for the Delhi region in Table 2. In Males the highest incidence of Oral Cancer was seen in 50-59 years age group for the year 2012-2014. The lowest incidence was seen below 20 years age group for the year 2006-2008. In Females the highest incidence of Oral Cancer was seen in 50-59 years age group for the year 2012-2014. The lowest incidence was seen below 20 years age group for the year 1990-1996.   Lip Cancer: In Males the highest incidence was seen in 50-59 years age group for the year 2006-2008. The lowest incidence was seen below 20 years age group for the year 1997-1998 and 2001-2008. It was also seen in the age group of 20-29 years for the year 1999-2003. In Females the highest incidence was seen in 50-59 years age group for the year 2012-2014. The lowest incidence was seen below 20 years age group for the year 1990-2000, 2004-2008 and 2012-2014. For the age group of 20-29 years it was seen in the year 1990-2003 and 2009-2011. For the age group of 30-39 years it was seen in the year 1990-1996, 1999-2000 and 2006-2008 (Table 3).     Tongue Cancer: In Males the highest incidence was seen in 50-59 years age group for the year 2006-2008. The lowest incidence was seen below 20 years age group for the year 2001-2011. In Females the highest incidence was seen in 50-59 years age group for the year 2012-2014. The lowest incidence was seen below 20 years age group for the year 1990-1996, 1999-2000 and 2004-2005 (Table 4).   Mouth Cancer: In Males the highest incidence was seen in 50-59 years age group for the year 2012-20014. The lowest incidence was seen below 20 years age group for the year 1990-1996. In Females the highest incidence was seen in 50-59 years age group for the year 2012-2014. The lowest incidence was seen below 20 years age group for the year 1990-1998, 2006-2008 and 2012-2014. For the age group of 20-29 years it was seen in the year 1990-1996 (Table 5).   Discussion   A significant increasing trend in Oral Cancer relative proportion rate in Delhi among all cancer sites from 2004 to 2014 has been observed which is also coordinating with the steady increase in Incidence of Oral cancer (lip, tongue and mouth) among males and females from 2004 to 2014 in all the age groups. Analysis of Delhi PBCR reports have revealed a direct relation of increasing incidence of Oral Cancer with the age, the highest incidence for both genders was seen in age group 50-59yrs and the lowest incidence for both genders was in youngest age group (<20 yrs) for all the years from 1990 to 2014. Studies from other PBCRs in India have largely reported similar trends among men and women. NCRP data from Mumbai show a steep increase of mouth cancer incidence in men from 1999 to 2009 (3.3% each year) and a slight increase among women from 2002 to 20092. South Asian countries such as India, Sri Lanka, Pakistan, Bangladesh and Taiwan report the highest incidence rates of oral cancer in the World due to betel quid and tobacco chewing habits, coupled with low awareness and health care access, and poor referrals of diagnosis and care. While Sri Lanka in recent years has shown a decreasing trend of oral cancers of about 1.9% per year (p < 0.05) in both men and women8, Taiwan9 and Pakistan10 have consistently showed increasing trends in both men and women. Among European countries with high incidence of oral cancer, rates in France and Slovakia have been decreasing among men and increasing among women11,12. Oral cancer trends have been decreasing in both men and women in all other developed countries except United Kingdom, Denmark and Netherlands, which show increases in recent years11,13,14. The decline in oral cancer incidence trends in most parts of the world, especially high income regions, is consistent with increased awareness and decline in tobacco use11. According to the recent National family health survey (NFHS-4) study for the year 2015-16, there were 38.9% men who use any kind of tobacco in urban while 48% in rural areas of India. On the other hand, 4.4% of women in urban and 8.1% in rural use any kind of tobacco. Prevalence of tobacco use in the ages of 13-15 among boys was 19% and girls 8.3 % according to global youth tobacco survey of 200915. Stringent tobacco control policies and programmes have been in place in India since 2004, including advertisements to be restricted only to point- of- sale, prohibition of sale of tobacco products to children less than 18 years of age and near educational institutions, health warnings, and declaration of product contents on packs5.         Out of all cancers, tobacco-related cancer (TRC) accounts for major share.  According to the World Health Organization (WHO), nearly 6 million deaths occur every year due to tobacco use, which may escalate to 8 million deaths a year by 2030 16. India has one of the highest tobacco users in the world both in number and relative share. Tobacco is used in India in many forms. Smoking of cigarettes and beedis (tobacco wrapped in dried leaves of special trees) is one form of tobacco use. Smokeless tobacco use consists of chewing pan (mixture of lime, pieces of areca nut, tobacco and spices wrapped in betel leaf), chewing gutkha or pan masala (scented tobacco mixed with lime and areca nut, in powder form), and mishri (a kind of toothpaste used for rubbing on gums). India is one of the fewer countries in the world where prevalence of smoking and smokeless tobacco use are high and is characterised by dual use of tobacco (use of both smoking and smokeless tobacco products). The emergence of newer, chewable flavored forms of tobacco along with several other ingredients, called gutka has changed the trends in the tobacco market17.Gutka contains areca nut, slaked lime, catechu, condiments, and powered tobacco. It was originally available custom?mixed from paan vendors. Gutka has been commercially available since 197518 and has been available in several brands for the last few decades. Gutka is exported to 22 countries worldwide, this shows its spreading usage. Numerous brands of paan-masalas and gutkhas are being advertised and sold in Indian markets without impunity in the name of flavor, fragrance and freshness. Due to its flavored taste, easy availability and cheapness, it is popular among poor children. Gutkha is sold as loose or in small pouches. The market of Gutkha in India is about worth of INR150bn?INR200bn19. Five million children in India are estimated to be addicted to gutka, who are under the age of 15 years18. Gutkha  is found to have 3095 chemical ingredients, of which 28 are proven carcinogens. We suspiciously assume the Gutkha as the main culprit, in causing the steep increase of Oral cancer incidence proportion as Gutkha gained its popularity in Delhi region in the last decade of the 20th Century.   Based on several reports indicating health hazards caused, efforts are undertaken to ban the production, consumption, sale, storage and transportation of gutkha and pan masala by many states in India. Tamil Nadu banned gutkha in 2001 followed by Andhra Pradesh, Goa, Maharashtra and Rajasthan in August 2002. Until May 2013, 26 states had banned gutkha. Gutkha is banned under the provision to ban any food product containing harmful adulterants in the centrally enacted Food Safety and Regulation (Prohibition) Act 2011.  Recognizing the significance of tobacco cessation, 13 tobacco cessation clinics (TCCs) were started in 2002 by the Ministry Of Health and Family Welfare, Government of India, with the support of World Health Organization India Country Office, and were increased to 19 in order to provide tobacco cessation interventions. To strengthen implementation of the tobacco control provisions the Government of the India piloted National Tobacco Control Programme (NTCP) in 2007–2008. The programme is under implementation in 21 out of 35 States/Union territories in the country. National Guidelines for Treatment of Tobacco Dependence have also been developed and disseminated by the Government in 2011, to facilitate training of health professionals in tobacco cessation15. With these recent developments in tobacco control, the incidence of mouth cancers was expected to decrease. However, to date the enforcement of these policies has been weak or insufficient6 which is reflected in the increasing trend observed in our study. The increasing trends of Oral cancer that we observed in Delhi, and in both men and women, has underscore the public health importance of targeted programmes to decrease the prevalence of risk factors in young men and women, as Delhi continues to observe increase in rate of Oral cancer.