Abstract
Background
For effective planning and optimum allocation of resources, accurate assessment of burden due to tobacco and its projection is essential. There are number of reports in India during last 3-4 decades, reporting tobacco related cancers (TRC). However, there is no visible study in India attempting to assess cancers due to tobacco (CDT).
Objectives
To assess CDT in India and States by sex and urban/rural and project the same till 2025.
Materials and methods
The basic inputs required were 1) tobacco prevalence, 2) relative risk of cancer due to tobacco, 3) incidence rates of TRCs, and, 4) population. These were obtained respectively from 1) recent five rounds of NSSO, 2) our recently published study, 3) reports of PBCRs, and, 4) projections of Registrar General of India. Our recently published method was applied to assess the CDT and regression method for projection.
Results
The overall burden of CDT in India was estimated to be 169 thousands in 2015 and it was projected to around 236 thousands by 2025, an increase of nearly 39.6%. CDT accounted for nearly half of TRCs. The CDT as percentage of TRC was highest for Tripura followed by Meghalaya, Manipur, Mizoram and West Bengal. Detailed analysis indicated regional diversity in both CDT and TRCs.
Conclusions
Present study reports absolute burden of CDT as well as the same as a percentage of TRC for India and its States till 2025. This may help policy planners and administrators in prioritizing the resources and proactive decisions pertaining to anti-tobacco measures. Non-availability of enough PBCRs to capture regional diversity may also be addressed by competent authorities.
Keywords
1. Introduction
In the world, around 6 million people die from tobacco use and second-hand smoke. Smoking has been reported to cause about 71% of lung cancer, 42% of chronic respiratory diseases and 10% of cardiovascular diseases. In addition, the prevalence of smoking among men is higher in lower-middle income countries whereas for the total population; it is higher in upper-middle income countries.
1
In India, tobacco problem is more complex than probably any other country in the world because of the various patterns of tobacco consumption like chewing, smoking, applying, sucking, gargling, etc., and a large consequential burden of tobacco-related diseases and death.In India, 10 million workers are employed in the tobacco industry, nearly 60% of them are women, and 12–15% of them are children mainly young girls.
3
These families have a high risk of lung diseases and cancer of the digestive tract because addiction is common among them.4
It also found regional diversity in burden of smoking and smokeless tobacco. Burden of tobacco smokers is projected to increase in urban India from 101.8 million in the year 2015 to 106.2 million by 2025.5
As a result, the incidence of tobacco related cancers like lips tongue, mouth, lungs, oropharynx etc. may also increase during 2015–2025.6
The number of tobacco attributable deaths in India in the late 1980s was also estimated to be 630,000 per year.7
Currently, conservative estimates of tobacco attributable deaths are reported to be between 800,000 and 900,000 per year.8
The extent of cancer incidence related to tobacco for India as a whole has been estimated according to the age,sex and site based on different methods till the years 2016, 2020 and 2025.
6
,9
,10
However, there is no visible published study that estimates directly or indirectly the incidence of cancer due to tobacco for India and its States. Even, the reports National Cancer Registry Programme (NCRP) tabulate only the tobacco-related cancers (TRCs). This is mainly due to 1) different forms of tobacco, and 2) varying degree of association of tobacco with different types of cancers. There is evidence of studies combining the outcomes of multiple exposures, however, the same were confined to the developed world, that too three to four decades ago.11
, 12
, 13
, 14
In India, recently Prasad and Dhar (2019), while narrating the method descriptively, worked out the CDT, however, scope of their study was limited to a particular State in India.15
Thus, there is no data on CDT in developing countries in general and India and its States in particular with the exception of only one State. Therefore, the objective of present study was to provide actual burden of CDT for India and its States/UTs and compare the same with TRCs.2. Materials and methods
A number of studies are available for the estimation and projection of all cancers in general and tobacco related cancers (TRCs) in particular in India.
6
,9
,10
However, there is no visible study to assess actual burden of cancers due to tobacco (CDT). Although, there is evidence of the studies dealing with multiple exposures associated with an outcome, the same has been confined to the developed world and there is no evidence of application during last three to four decades. In view of the same, Prasad and Dhar narrated the method descriptively for the assessment of CDT in India in view of multiple forms of same exposure. The method is essentially based on and is an extension of the concept of population attributable risk (PAR).15
Application of the method for assessment of CDT in India required data on cancer incidence, prevalence of different forms of tobacco use and relative Risk/Odds Ratio.- (a)Cancer incidence
Although the history of cancer registration in India is older than a half decade, the data on cancer registration is very limited in terms of geographical coverage. Population based cancer registries in India convers less than or about 10% of national population most of which is from urban areas.
16
Under the circumstances, there has been many attempts to estimate and project the national burden of cancer incidence. Latest has been by Prasad and Dhar (2018), who estimated the cancer incidence in India by State/Union Territories and projected the same till 2025.6
Present study utilized the estimates and projections of cancer incidence from this study.- (b)Prevalence of different forms of tobacco use
Global adult tobacco survey (GATS) is the most recognized and comprehensive source of data on tobacco use in India. This survey was conducted during 2016–2017.
17
In addition, National Sample Survey Organization (NSSO) also collects data on tobacco use in selected rounds. Latest round of NSSO dealing with the data on tobacco use was conducted in 2011–12. Utilizing these data, Prasad and Dhar (2017) worked out and projected till 2025 the prevalence of different form of tobacco use in India.5
Present study utilized the estimates and projections of cancer incidence from this study.- (c)Relative risk/odds ratio
Relative risk (RR) as such are obtained from cohort studies which are almost perhaps non-existent for cancer at least in the setup of developing countries including India. The main reason being the typical one, non-feasibility of cohort study design for relatively rare diseases. Case-control studies however give a good estimate of RR in the form of odds ratio (OR) under certain assumptions. Cancer being relatively a rare disease provides perfect case of the conduct of case-control studies and this design is known to provide good estimate of RR, especially if conducted with population based controls. There are a number of case-control studies conducted in the past to estimate RR of different forms of cancer associated with different forms of tobacco use. Different studies, however, provide varying estimate of RR for same exposure and outcome. In view of this, Prasad and Dhar (2018) conducted a meta-analysis and reported pooled estimate of RR for different combinations of exposure (different forms of tobacco use) and outcome (different cancers associated with tobacco use.
18
Present study utilized the required data on RR from this study.3. Results
3.1 CDT vs TRC by site
The burden of tobacco related cancers (TRCs) was estimated to be about 365 thousand in 2015. However, less than half of these were the cancers due to tobacco (CDT). Thus the burden due to tobacco are more than doubled when assessing in terms of TRC. Lung was the main contributor to the TRC accounting for 30% followed by mouth (20%), tongue (14%) and esophagus (13%). Among CDT also, the main contributing sites were on the lines of TRC except that the sites at third and fourth rank were interchanged. Looking at the proportion of TRCs that are due to tobacco, it was highest for oropharynx (60%) followed by larynx (57%), mouth (55%) and lung (53%). It was lowest for the site of lip, about quarter of lip cancers are due to tobacco. CDT was projected to increase from 169 thousand in 2015 to 202 thousand by 2020 and 236 thousand by 2025, an increase of 15–20% every five years. Relative contribution of CDT among TRC remained almost same over the study projection period (Table 1).
Table 1Number of tobacco-related cancers (TRCs), cancer due to tobacco (CDT) and percent CDT as of TRCs by sites in India, 2015-25.
| Sites | TRCs | CDT | CDT as % of TRCs | ||||||
|---|---|---|---|---|---|---|---|---|---|
| 2015 | 2020 | 2025 | 2015 | 2020 | 2025 | 2015 | 2020 | 2025 | |
| Lip | 3,620 | 4,172 | 4,755 | 989 | 1,135 | 1,290 | 27.3 | 27.2 | 27.1 |
| Tongue | 52,256 | 63,988 | 76,273 | 19,911 | 24,386 | 28,956 | 38.1 | 38.1 | 38.0 |
| Mouth | 72,367 | 91,023 | 1,11,764 | 39,445 | 49,755 | 60,648 | 54.5 | 54.7 | 54.3 |
| Oropharynx | 5,333 | 6,232 | 7,201 | 3,195 | 3,710 | 4,251 | 59.9 | 59.5 | 59.0 |
| Hypopharynx | 19,050 | 19,986 | 20,746 | 9,198 | 9,504 | 9,688 | 48.3 | 47.6 | 46.7 |
| Pharynx Unsp. | 4,020 | 4,476 | 4,915 | – | – | – | – | – | – |
| Esophagus | 46,088 | 49,733 | 53,006 | 21,672 | 23,331 | 24,771 | 47.0 | 46.9 | 46.7 |
| Larynx | 30,389 | 32,876 | 35,204 | 17,442 | 18,841 | 20,073 | 57.4 | 57.3 | 57.0 |
| Lung | 1,07,559 | 1,34,189 | 1,62,273 | 57,332 | 71,720 | 86,800 | 53.3 | 53.4 | 53.5 |
| Urinary Bladder | 24,476 | 27,242 | 30,170 | – | – | – | – | – | – |
| Total | 3,65,158 | 4,33,917 | 5,06,307 | 1,69,184 | 2,02,382 | 2,36,477 | 46.3 | 46.6 | 46.7 |
3.2 CDT by State/UT
As stated earlier, the burden of CDT in India was estimated at 169 thousand in 2015 and projected to increase to 236 thousand by 2025. Most of this burden was contributed by the larger states like, Uttar Pradesh followed by Bihar and West Bengal. Smaller States/UTs like Lakshadweep had little significance in overall CDT burden in India. CDT showed increasing trend during the study period 2015 to 2025 in almost in all States/UTs. Relative contribution of CDT among TRC was higher side (up to two thirds) in some of the north eastern States, namely, Tripura, Meghalaya, Mizoram and Manipur. Next were a group of states from northern part of the country where about half of the TRCs were CDT. These states were Rajasthan, Uttar Pradesh, Bihar, Jammu Kashmir, Himachal Pradesh, Uttaranchal and Arunachal Pradesh. With the exception of Chhattisgarh during both time periods and Karnataka and Goa during 2020–25, all the States/UTs (Table 2).
Table 2Cancer due to tobacco (CDT), CDT as % of TRCs and % change in CDT in India and its states, 2015-25.
| States/UTs | CDT | CDT as % of TRCs | % change in CDT | |||||
|---|---|---|---|---|---|---|---|---|
| 2015 | 2020 | 2025 | 2015 | 2020 | 2025 | 2015–20 | 2020–25 | |
| Jammu & Kashmir | 1213 | 1286 | 1345 | 49.0 | 49.5 | 50.0 | 6.0 | 4.6 |
| Himachal Pradesh | 680 | 720 | 756 | 48.3 | 48.8 | 49.8 | 5.9 | 5.0 |
| Punjab | 1838 | 2000 | 2151 | 31.2 | 32.0 | 33.5 | 8.8 | 7.6 |
| Chandigarh | 99 | 133 | 169 | 29.0 | 30.7 | 32.5 | 34.3 | 27.1 |
| Uttaranchal | 1378 | 1683 | 2004 | 48.7 | 50.2 | 51.8 | 22.1 | 19.1 |
| Haryana | 3286 | 3523 | 3739 | 44.2 | 44.0 | 44.4 | 7.2 | 6.1 |
| Delhi | 2539 | 3431 | 4530 | 43.8 | 45.7 | 47.7 | 35.1 | 32 |
| Rajasthan | 9010 | 9758 | 10,490 | 52.1 | 52.7 | 53.7 | 8.3 | 7.5 |
| Uttar Pradesh | 29,681 | 35,532 | 41,549 | 50.9 | 51.2 | 51.2 | 19.7 | 16.9 |
| Bihar | 23,679 | 32,570 | 42,244 | 52.6 | 56.1 | 58.8 | 37.5 | 29.7 |
| Sikkim | 56 | 61 | 67 | 46.6 | 45.7 | 44.8 | 8.9 | 9.8 |
| Arunachal Pradesh | 74 | 79 | 83 | 49.6 | 50.4 | 50.0 | 6.8 | 5.1 |
| Nagaland | 196 | 199 | 200 | 46.9 | 45.2 | 43.5 | 1.5 | 0.5 |
| Manipur | 228 | 240 | 251 | 58.9 | 58.6 | 58.6 | 5.3 | 4.6 |
| Mizoram | 300 | 387 | 481 | 58.6 | 61.8 | 64.2 | 29 | 24.3 |
| Tripura | 546 | 590 | 630 | 66.4 | 68.5 | 69.9 | 8.1 | 6.8 |
| Meghalaya | 647 | 679 | 708 | 60.8 | 60.6 | 60.7 | 4.9 | 4.3 |
| Assam | 5432 | 5693 | 5922 | 56.1 | 55.1 | 54.2 | 4.8 | 4.0 |
| West Bengal | 22,634 | 29,349 | 36,335 | 56.0 | 56.7 | 57.2 | 29.7 | 23.8 |
| Jharkhand | 5831 | 7636 | 9446 | 40.3 | 40.3 | 40.2 | 31 | 23.7 |
| Orissa | 7510 | 9760 | 12,084 | 41.1 | 41.9 | 42.5 | 30 | 23.8 |
| Chhattisgarh | 1625 | 1591 | 1445 | 44.1 | 38.3 | 30.5 | −2.1 | −9.2 |
| Madhya Pradesh | 11,484 | 12,248 | 12,413 | 54.2 | 50.2 | 45.0 | 6.7 | 1.3 |
| Gujarat | 7310 | 9289 | 11,314 | 37.1 | 37.2 | 37.2 | 27.1 | 21.8 |
| Daman & Diu | 41 | 68 | 98 | 36.5 | 39.1 | 40.8 | 65.9 | 44.1 |
| Dadra & Nagar Haveli | 49 | 60 | 67 | 46.1 | 44.9 | 44.8 | 22.4 | 11.7 |
| Maharashtra | 8206 | 8938 | 10,059 | 39.7 | 38.8 | 37.8 | 8.9 | 12.5 |
| Andhra Pradesh | 5321 | 5831 | 6593 | 39.1 | 39.0 | 38.9 | 9.6 | 13.1 |
| Karnataka | 5018 | 5039 | 4647 | 33.8 | 29.8 | 24.6 | 0.4 | −7.8 |
| Goa | 77 | 82 | 79 | 19.3 | 16.8 | 13.1 | 6.5 | −3.7 |
| Lakshadweep | 6 | 6 | 6 | 20.0 | 18.3 | 18.7 | 0.0 | 0.0 |
| Kerala | 5981 | 6300 | 6646 | 43.9 | 44.0 | 44.1 | 5.3 | 5.5 |
| Tamil Nadu | 7004 | 7383 | 7665 | 30.0 | 29.0 | 27.7 | 5.4 | 3.8 |
| Pondicherry | 133 | 154 | 163 | 23.3 | 20.2 | 16.9 | 15.8 | 5.8 |
| A & N Islands | 73 | 86 | 99 | 39.3 | 39.3 | 39.0 | 17.8 | 15.1 |
| India | 169,185 | 202,384 | 236,478 | 46.3 | 46.6 | 46.7 | 19.6 | 16.8 |
Table 3Top 10 States/UTs according to tobacco related cancers (TRCs) and cancers due to tobacco (CDTs) in India.
| Rank | According to TRCs | According to CDT |
|---|---|---|
| 1 | Uttar Pradesh | Uttar Pradesh |
| 2 | Bihar | Bihar |
| 3 | West Bengal | West Bengal |
| 4 | Tamil Nadu | Madhya Pradesh |
| 5 | Madhya Pradesh | Rajasthan |
| 6 | Maharashtra | Maharashtra |
| 7 | Gujarat | Orissa |
| 8 | Orissa | Gujarat |
| 9 | Rajasthan | Tamil Nadu |
| 10 | Karnataka | Kerala |
3.3 Leading States/UTs
In terms of absolute number, Uttar Pradesh was the leading state followed by Bihar and West Bengal accoding to TRC as well as CDT. Beyond third rank however, there were substantial variation in the ranks of States/UTs according to TRC and CDT. Tamil Nadu ranked 4th according to TRC slipped down to 9th according to CDT. On the other hand, Rajasthan ranked 9th according to TRC was actually the 5th highest contributor to the national burden of CDT. The comparison of ranks according to absolute and relative burden of TRC was on the technically expected lines. Leading States/UTs according to burden of TRC as proportion of population were Mizoram, West Bengal, Meghalaya and Bihar in the order. Uttar Pradesh, the leading State according to absolute burden was beyond 10 according to burden relative to population had highest burden of cancer attributable to tobacco followed by the Bihar, West Bengal, Madhya Pradesh, Rajasthan, and Maharashtra. However, in relative number, Mizoram is in the top one followed by West Bengal, Meghalaya, Bihar, Orissa and so on. If we are looking in top ten states/UTs according to TRCs and CDT, which are shown in Table 4. We found that Uttar Pradesh is in top one in both TRCs and CDT. Tamil Nadu is at fourth rank in TRCs, however, in CDT, it is at ninth rank. Similarly, Rajasthan is at ninth rank in TRCs, however, in CDT it is at fifth rank. Karnataka is the state, which comes under the 10th rank in TRCs however, in CDT, it is out of top ten ranks. In general, rank of the states/UTs in TRCs and CDT may or may not be the same (Table 3, Table 4).
Table 4Top 10 States/UTs according to absolute and relative burden of cancers due to tobacco (CDTs) in India.
| Rank | According to absolute burden | According to relative burden |
|---|---|---|
| 1 | Uttar Pradesh | Mizoram |
| 2 | Bihar | West Bengal |
| 3 | West Bengal | Meghalaya |
| 4 | Madhya Pradesh | Bihar |
| 5 | Rajasthan | Orissa |
| 6 | Maharashtra | Jharkhand |
| 7 | Orissa | Assam |
| 8 | Gujarat | Kerala |
| 9 | Tamil Nadu | Madhya Pradesh |
| 10 | Kerala | Tripura |
4. Discussion
The concept of combining the outcomes of multiple exposures is not so complex or difficult. Therefore, there is evidence of methodological work on this concept as early as about 4 decades ago.
11
, 12
, 13
The application of the same however is not visible for 3 to 4 decades, may be due to complexities involved in empirical application. Even the initial work on this concept has been confined to the developed world, although, the requirement may be more in the developing world due the complex forms of uses of same basic substance. Even after over half century of cancer registration in India, the cancer registry reports, whether individual or consolidated, have been presenting the tobacco related cancers (TRCs). There is no visible attempt to find out how much of TRCs are actually due to tobacco. It can be even a layman's understanding that not all the TRCs are due to tobacco. The important additional fact however is that different cancer sites related to tobacco use are associated with different forms of tobacco use with varying value of relative risk. Even the prevalence of different forms of tobacco use has considerable variation. For an accurate and effective policy planning, accurate burden of cancers due to tobacco are necessary. The proportion of cancers of different tobacco related sites that are actually due to tobacco are also needed to be known for micro level planning. Therefore, this study was undertaken to report the cancer due to tobacco by States/UTs and site and also the ranking of States/UTs and tobacco related sites according to TRCs and absolute and relative burden of CDTs.Unlike developed world, developing countries including India do not have sufficient information on cancer. As per current report of PBCR India, there are 31 cancer registries which are working in 16 states and 2 union territories (UTs). Remaining 18 States/UTs have no cancer registry till date. However, for estimation of burden of cancer due to tobacco for India as whole, there is need to estimate the state-wise burden of cancer related to tobacco. For this, study utilized the estimates provided in a published paper by Prasad and Dhar in 2018.
6
Prasad and Dhar also enumerated the method for multiple exposures and multiple outcomes which were published with a suitable application in year 2019.15
Thus, Prasad and Dhar (2019) generalized method has been found appropriate for estimating the burden of cancer cases due to tobacco for all states of India and country as a whole.In India, burden of tobacco-related cancer and cancer due to tobacco vary by sites and region. Some other study indicates that mortality rates due to tobacco-related cancer vary widely across regions, but prevalence and rates of incidence are highest in developing countries such as India, Pakistan, and Bangladesh, where tobacco-related cancers are the most common forms of cancer.
19
,20
Out of ten sites, lung cancer cases were found to be high due to tobacco, which shows increasing trends from the year 2015–2025. It may be because of high burden of smoking tobacco users.5
Some study also supported and indicates that bidi smoking has a greater risk in developing the cancer of lung, oropharynx and esophagus.18
, 19
, 20
, 21
, 22
Mouth cancer is a second large burden among all ten TRCs site. Out of all tobacco related mouth cancer, around 55% are due to tobacco. Higher risk of these oral caners is due to betel-quid chewing tobacco.
23
A similar risk level is also observed in Prasad and Dhar (2018) published article and shows higher risk is because of chewing tobacco.24
The risk of oral cancer was higher among females, most likely because of the nature of their mucosa, which is more susceptible to spoil on exposure to tobacco, and/or lack of knowledge and awareness about tobacco use.25
,26
In addition, Bihar and Uttar Pradesh is most populous states and shown high burden of smokeless tobacco consumption,5
which may be one of the reasons of high burden of oral cancer in the country. This study also indicates that more than 50% cancers cases are due to tobacco consumption among all tobacco related cancers in the respective states.Rank of states/UTs as per absolute and relative burden is not same. Similarly, rank of states/UTs in TRCs and CDT are different except some bigger states/UTs like Uttar Pradesh, Bihar, West Bengal etc. Uttar Pradesh is at top one rank in absolute burden of cancer followed by Bihar, West Bengal, Madhya Pradesh, Rajasthan, Maharashtra, Orissa, Gujarat, Tamil Nadu and Kerala. However, in relative burden of cancer, Mizoram is at number one rank followed by West Bengal, Meghalaya, Bihar, Orissa, Jharkhand, Assam, Kerala, Madhya Pradesh and Tripura. This indicates that burden of cancer depend not only population but prevalence of exposure (forms of tobacco) and risk of cancer also in the geographical regions.
5. Conclusion
Finding of this study indicates regional diversity in burden of CDTs. Uttar Pradesh, Bihar and West Bengal has shown high and increasing trends over the periods. In Manipur, Mizoram, Tripura, Meghalaya and Assam, number of cancer cases due to tobacco is around 60% of respective states TRCs followed by West Bengal (56%), Madhya Pradesh (54%), Bihar (53%), Rajasthan (52%), Uttar Pradesh (51%) and so on. In addition, around in all states/UTs, percent change in CDTs is going down throughout the period 2015–20 and 2020–25 resultants percent change slightly decreased in the country as whole. However number of cancer cases in the country is increasing due to high burden of cancer in most populous states as well as in northeast. In order to reduce the cancer cases from the country, there is need to focus highly cancer concentrated states and conduct district wise research to specify smallest geographical area for special focus.
Acknowledgements
Not applicable.
Availability of supporting data
This study is based on Secondary data, which is available online at different Website as mention in materials and methods sections.
Funding source
Not applicable.
Ethical clearance
Not applicable.
Declaration of competing interest
We hereby declare that the article entitled “Assessment and projection of burden of cancer due to tobacco in India till 2025” does not have any conflict of interest involved.
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Article info
Publication history
Published online: April 01, 2020
Accepted:
March 19,
2020
Received in revised form:
March 5,
2020
Received:
February 15,
2020
Identification
Copyright
© 2020 INDIACLEN. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.
