The study was conducted by Professor Prabhat Jha, Center for Global Health Research, St. Michael's Hospital and University of Toronto, ON, Canada, and colleagues across India and worldwide.
In India, approximately 75% of individuals live in rural areas. However, estimated mortality rates for specific cancers have primarily been based on data from India's 24 urban population-based cancer registries, with only 2 registries representing rural areas.
As a result, the team set out to evaluate cancer mortality in the Million Death Study (MDS). The MDS is one of the few large, nationally representative studies (including rural areas) of the causes of mortality in any low- or middle-income country and is conducted by the Office of the Registrar General of India.
The researchers focused on the social and geographical variation in specific cancers, as well as the extent to which these cancers might be preventable by managing their causative agents or risk factors.
The team discovered that of the 122,429 deaths reported in the study, 7,137 were caused by cancer. This figure is equal 556,400 cancer deaths across the entire country of India in 2010.
Of these 556,400 deaths, 71% (395,000 [195,300 women and 200,100 men]) occurred in individuals aged between 30 and 69 years. For all age groups, the team found that cancer was responsible for 6% of the 2.5 million total male deaths and 1.6 million total female deaths, however this figure rose to 8% among the 30-69 years age group.
According to the researchers, the three leading causes of cancer death in men aged 30-69 years were:
- Lung cancer (including larynx and trachea) - 11% (22,900)
- Oral cancer (including pharynx and lip) - 23% (45,800)
- Stomach cancer - 13% (25,00)
- Breast cancer - 10% (19,900)
- Cervical Cancer - 17% (33,400)
- Stomach Cancer - 14% (27,500)
The researchers explained:
"The number of oral cancers was more than twice the number of lung cancers in individuals aged 30-69 years, indicating that the range of fatal cancers caused by tobacco in India differs substantially from that in high-income countries."
Although results showed that age-standardized cancer mortality rates per 100,000 were comparable in rural and urban ages (men 96, women 97 vs. men 102, women 91 respectively), they varied considerably between the states.
They found that mortality rates were twice as high in the least educated (107 men, 107 women) than in the majority of educated adults (46 men, 43 women). In addition, the prevalence of cervical cancer was 40% less in Muslim women than in Hindu women. According to the researchers, this may be due to high circumcision rates among Muslim men having a protective effect against human papillomavirus (HPV) infection, which can cause cervical cancer.
Furthermore, results from the study showed that men aged 30 in northeastern India had the greatest risk (11.2%) of dying from cancer before the age of 70. However, in the adjacent states of Odissa, Bihar, and Jharkhand in eastern India, the death risk for men was less than 3%. In addition, women in the northeastern states of India had the greatest risk (6.0%) of dying from cancer before the age of 70.
Cancer mortality rates in India are approximately 40% lower in adult men and 30% lower in women than rates in the UK or United States. However, cancer mortality rates are expected to increase, particularly with increases in age-specific rates of tobacco smoking.
The researchers conclude:
"Prevention of tobacco-related and cervical cancers and earlier detection of treatable cancers would reduce cancer deaths in India, particularly in the rural areas that are underserved by cancer services. The substantial variation in cancer rates in India suggests other risk factors or causative agents that remain to be discovered."
In a joint comment, Dr. Dr Rengaswamy Sankaranarayanan, International Agency for Research on Cancer, Lyon, France, and Dr Rajaraman Swaminathan, Department of Biostatistics and Cancer Registry, Cancer Institute (WIA), Chennai, India, said:
"The fact that 71% of cancer deaths occur in those aged 30-69 years emphasizes the substantial social and economic gains that would be associated with a successful cancer prevention program.
Interventions such as tobacco control, vaccination against human papillomavirus and hepatitis B, cervical cancer screening, and early detection and treatment of oral and breast cancers would have a substantial effect on the prevention of cancer deaths."
Written by Grace Rattue