|Year : 2019 | Volume
| Issue : 6 | Page : 503-507
Investigation of a cancer cluster in an industrial area of North India
Vijay Kumar Barwal1, Shishupal Singh Thakur2, Sanjay Kumar3, Salig Ram Mazta4, Anmol Gupta1, Ankit Chaudhary1
1 Department of Community Medicine, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India
2 Department of Community Medicine, Shri Lal Bahadur Shastri Government Medical College, Mandi, Himachal Pradesh, India
3 Department of Community Medicine, Dr. S Radhakrishnan Government Medical College, Hamirpur, Himachal Pradesh, India
4 Department of Community Medicine, Dr. YS Parmar Government Medical College, Nahan, Himachal Pradesh, India
|Date of Submission||27-Nov-2018|
|Date of Acceptance||29-Mar-2019|
|Date of Web Publication||17-Oct-2019|
Vijay Kumar Barwal
Department of Community Medicine, Indira Gandhi Medical College, Shimla, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Cancer clusters always get a lot of attention in the media. It is an aggregation of relatively unexpected high number of cancer cases. People become concerned that a cancer cluster exists in a certain community and that it is caused by some type of carcinogen that is being released into the environment. We investigated a similar concern regarding suspected clustering of cancer cases in an industrial area of a district in North India. Materials and Methods: A retrospective cohort study was carried out from March 1, 2016, to May 31, 2016 taking the whole study area population as exposed. House-to-house search of cancer cases was undertaken retrospectively from the year 2011 onward. The total population of the cohort (denominator) was taken from the census of India 2011 data. Age-adjusted standardized rates were calculated. Results: A total of 53 cancer patients were identified. A maximum number of cases were of the lip and oropharynx (15.1%), followed by the lung (13.2%) and esophagus. The yearly incidence of cancer for both sexes ranged from 87.2 to 90.9/lakh population. The 5-year period prevalence for both sexes was 207.4/lakh population. Conclusion: This panic occurred due to a list of cancer cases given to the health department by the residents and public representatives of the area. As these were just figures without a denominator, it gave a false impression of a high number of cancer cases. However, on conducting this study, we found the age-adjusted cancer incidence to be similar or even lower than the Global Cancer Incidence, Mortality and Prevalence, and Indian Council for Medical Research figures for India. Hence, we ruled out a true cancer cluster.
Keywords: Cancer cluster, incidence, mortality from cancer, prevalence
|How to cite this article:|
Barwal VK, Thakur SS, Kumar S, Mazta SR, Gupta A, Chaudhary A. Investigation of a cancer cluster in an industrial area of North India. Med J DY Patil Vidyapeeth 2019;12:503-7
|How to cite this URL:|
Barwal VK, Thakur SS, Kumar S, Mazta SR, Gupta A, Chaudhary A. Investigation of a cancer cluster in an industrial area of North India. Med J DY Patil Vidyapeeth [serial online] 2019 [cited 2020 Dec 4];12:503-7. Available from: https://www.mjdrdypv.org/text.asp?2019/12/6/503/269425
| Introduction|| |
Cancer clusters always get a lot of attention in the media, both in the news as well as in the movies. It is an aggregation of a relatively unexpected high number of cases in a given area.
People may become concerned that a cancer cluster exists in a certain community, and it is being caused by some type of carcinogen that is being released into the environment.,
Himachal Pradesh being one of the hilly states of India, but having relatively good development indices have seen a recent development and mushrooming of industries in its southern district of Solan. People in this region have become apprehensive about these industries, and the toxic wastes being released into the air as well as liquid waste contaminating the groundwater.
We did an investigation regarding this concern of residents about clustering of cancer cases in the two health blocks of this district.
| Materials and Methods|| |
On the directions of the State National Health Mission (NHM), Himachal Pradesh, a retrospective cohort study was planned. We went back in time and took the whole population in the year 2011 as exposed population. The data collection was done from March 1, 2016 to May 2016. The local residents and the public representatives of two health blocks of Nalagarh and Chandi, in district Solan, had raised the issue of clustering of cancer cases in their area which consists of 11 gram panchayats. These were Barotiwala, Saned, Kishanpura, Bhatoli kalan, Lodhimajra, Malpur, Nandpur, Manpura, Haripur sandoli, Manjholi, and Khera. Most of the industrial units have sprung up between the years 2001 and 2010, making the area as an important industrial hub of Himachal Pradesh. As this issue had various social and political implications, we got an urgent message from the office of state NHM to investigate the clustering of cancer cases in this area of district Solan.
Starting retrospectively from the year 2011, the whole population of the study area was taken as exposed population. It constituted all the permanent residents of 11 gram panchayats as per the census of India 2011 data. An extensive house-to-house search was undertaken to find how many out of the exposed persons developed cancer in the year 2011 and later.
A semi-structured data collection tool was designed, which was pretested in the Department of Radiotherapy and Oncology, Regional Cancer Centre, Indira Gandhi Medical College (IGMC) Shimla. It was designed by the public health and cancer experts. It consisted of sociodemographic profile of the cases, their food habits, alcohol and tobacco use, family history of cancer, sign and symptoms, date of onset and diagnosis, type of cancer, date of death, and any other relevant details.
A three-member team from the Department of Community Medicine, IGMC, Shimla, was constituted to investigate the cluster. Data collection tool was filled up for all the cancer cases which were diagnosed or had died in the year 2011 or later out of the exposed population. Similarly, the data collection tool was also filled up for the prevalent cases. Records of the patients under treatment were noted down with their diagnosis. For patients who had died, the diagnosis of cancer was arrived at after conducting a detailed interview and noting down the narrative with sign and symptoms as told by the nearest relative of the cancer patient. The diagnosis was done with the consensus of two physicians. If there was disagreement, then a third senior physician's opinion regarding the diagnosis of cancer was taken. Wherever available, the death certificates of the cancer cases were seen to confirm the date of death. During the field visits, health workers and Accredited Social Health Activists (ASHA) of the respective areas accompanied the team as local guides.
Permission to conduct the study was taken from the institutional ethics committee. Informed and written consent was obtained from all the participants, that is, the cancer cases or their relatives before conducting the detailed interviews and filling up the questionnaires. They were guaranteed about the confidentiality of each participant.
The total population of the cohort was taken from the census of India 2011 data, which was used as the denominator. The mid-year denominator population was calculated by taking the yearly growth rate of 1.3% for our state of Himachal Pradesh. The population of the 5 years age groups was taken from the department of economics and statistics, Himachal Pradesh, Shimla. To help in comparison, direct method of standardization and world standard population were used to calculate the incidence and mortality rates. Data were collected, entered, and analyzed in Microsoft Office Excel software.
| Results|| |
A total of 53 patients with a history of cancer or having treatment records and diagnosed with cancer were identified through active house-to-house search by the team. Of these, 30 (57.7%) patients were male. These cases ranged from January 1, 2011 to December 2015. Of these, 15 cases were under treatment, 13 of these were taking treatment from PGI Chandigarh, whereas the rest had succumbed to the disease. Records of only 17 patients (including 15 under treatment) were available at the time of this study.
A maximum number of cancer cases were of lip and oropharynx (15.1%), followed by lung (13.2%), esophageal cancer (9.4%), and larynx, stomach, and liver (all 7.5% each) [Table 1].
Eighteen (34%) cancer patients had a history of consumption of alcohol, and 25 (47%) had a history of tobacco use, 14 (26%) were nonvegetarians, and 10 (19%) had a family history of cancer in a first-degree relative.
For calculating the incidence and prevalence of cancer cases, we took the cases from the year 2011 onward. All the cases which were diagnosed or under treatment or had died during this period were included. The yearly incidence of cancer ranged from 86.6 to 93.5 in females and 85.5 to 93.0 in males, whereas for both sexes it was 87.2–90.9/lakh population. Similarly, the mortality rate ranged from 87.4 to 90.3/lakh population for both sexes, whereas the 5 years prevalence for both sexes was 207.4/lakh population [Table 2],[Table 3],[Table 4].
| Discussion|| |
We found a wide variety of cancers, but these cancers were the usual common types of cancers found in India. There is no single common carcinogen known which leads to all of these cancers [Table 1]. Most of them have different etiologies. According to the Indian Council of Medical Research (ICMR), most common types of cancers in males are mouth/pharynx, esophagus, stomach, and lung/bronchi, whereas in females, the common cancers are cervix, breast, mouth/oropharynx, and esophagus. We also found a similar pattern in our study. On the other hand in Himachal Pradesh, the most common cancer in males is that of lung, whereas it is cervical cancer in females. Majority of cancer cases are known to occur in the age group between 30 and 69 years (71%). In our study also, we found 42 cases (79%) were in this age group, that is, from fourth-to-seventh decade of life.
Eighteen (34%) of the cancer patients had a history of consumption of alcohol, and 25 (47%) patients had a history of tobacco use, both of which are known to cause cancers such as oropharynx, larynx, esophagus, stomach, bladder, liver, and colorectum. Fourteen (26%) were nonvegetarians which are known risk factor for esophageal and stomach cancer. Ten patients (19%) had a family history of cancer in a first-degree relative.,
The yearly incidence of cancer (years 2011–2015) ranged from 86.6 to 93.5 for males and 87.2 to 90.9 for females, whereas the overall incidence for both sexes was 87.2–90.9/lakh population. This is similar to Global Cancer Incidence, Mortality and Prevalence (GLOBOCAN) 2013 report for India which is 92.4, 97.4, and 94.0/lakh population for males, females, and both sexes, respectively. However, as per the ICMR annual report 2016–2017, the age-adjusted cancer incidence in our study was found to be lower than the National Average of 104.7 for males and 102.3 for females. The 5-year period prevalence for both sexes in the area comes out to be 207.4/lakh population, which is comparable with the national 5-year prevalence of 202.9/lakh population. Although for males, it was higher at 197.1, and for females, it was lower at 227.4 as compared to GLOBOCAN figures of 146.6 and 262.5/lakh population, respectively.
The age-adjusted cancer deaths of 88.1/lakh/year for both sexes was higher in our study as compared to 51.2 in Talwandi Sabo and 30.3 in Chamkaur Sahib in Punjab.
It is always a big challenge for the health authorities and the investigating team to investigate a cancer cluster and comment on the chances of presence or absence of a true cluster. We ruled out the existence of a cancer cluster in the region, taking into consideration the following supporting evidence.
- Cancer cluster is defined if there are more than expected numbers of cancer cases or same type of cancer or different type, but with same etiology, or a rare type of cancer in the specific group of people. But contrary to this, we found all the common types of cancers which have different etiologies or risk factors (though a few risk factors may overlap). Moreover, we did not find any rare type of cancer,
- Cancer is a common group of diseases. It is fairly common for several people to develop cancer in small area around the same time. One of every three people is expected to be diagnosed with cancer at some point during his or her lifetime
- Some increase in the prevalence is bound to occur due to better diagnostic modalities and increase in access to the health services. Increase in population as well as the life expectancy may also add to the prevalence. Contrary to this, still we did not find any significant increase in the 5-year prevalence
- The long-latency period of majority of cancers complicates and confuses our attempts to associate cancers occurring at a given time in a community with local environmental contamination. There is often a period of many years to decades between the time of exposure which initiates and promotes cancer process to the development of a clinically detectable disease.,
Hence, it is recommended that a population-based cancer registry should be started in the district or state as a whole. It will register new cases of cancer in that geographical area. Only then, we will be able to know the actual incidence as well as the future trend in cancer cases, whether it is increasing or decreasing.
To win back the confidence of local residents and considering their apprehension about the cause of environmental factors/pollutants for the cause of cancer in the area, there should be increased surveillance and regular monitoring of air and underground water quality in the industrial area. This opportunity of increased awareness about cancer can be utilized to sensitize them about the preventive measures for various cancers with intensified information, education, and communication activities. For this, a list of symptoms of cancer can be given to the people to recognize early symptoms of cancer. Those who suspect they are suffering from the disease can be asked to undergo all tests to confirm it. The diet and living style are important factors to control the spread of cancers, and hence, we should be careful about these facts also.
One of the limitations of our study was that records of only 17 patients were available at the time of the visit, 15 of those were under treatment. Even the death certificates did not mention the cause of death. Hence, the cancer diagnosis was done on the basis of the narrative of the relatives (verbal autopsy).
This was a retrospective cohort study done on an urgent basis. However, considering the methodological limitations of this study, the findings need to be considered as preliminary, and there is a need for future detailed analytical study taking an appropriate control group.
| Conclusion|| |
All of this panic occurred due to a list of cancer cases given to the health department by the residents and public representatives of the area. Some of the cases in the list had died 10–15 years ago. As these were just figures without a denominator, it gave a false impression of a high number of cancer cases. However, on conducting this study, we found the age-adjusted cancer incidence to be similar or even lower than the GLOBOCAN and ICMR figures for India., Therefore, in light of our findings, it did not appear to be a true cancer cluster.
As such cancer is a common disease and considering the worldwide trend of rise in cancer cases, in the future, more such clusters may have to be investigated. Hence, this study may help the researchers in doing such an investigation, particularly in the setting of a low-middle-income country like India.
We are grateful to the National health Mission, Himachal Pradesh for providing the transport as well as boarding and lodging facilities during the investigation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]