This is a statement that needs to be interpreted carefully. There are many reasons leading to more number of cancer cases, but we don’t know for sure if the increased number of cases is due to risk factors. First, let’s see the list of what is leading to more cancer cases:
- The rising population is leading to more number of cases. For example, if one percent population has cancer then with a population of one million and ten million will have 10,000 and 100,000 cancer cases respectively.
- Cancer is a disease of old age. With improving life expectancy - people are living longer. Previously, people died of infections, malnutrition, natural calamities, and wars and never survived to reach age, where cancer starts to develop. This is now changing.
- More awareness regarding cancer in general population. People get themselves investigated early for new-onset symptoms rather than waiting.
- Increase in investigations for unrelated reasons picking up cancer incidentally. For example - ultrasound of abdomen for gall bladder stone picks up small kidney tumor. This way increasing numbers of cancers are being detected. Kidney cancers, thyroid cancers are being picked up incidentally because of rising rates of imaging for unrelated reasons. There is a medical term for these tumors- INCIDENTALOMAS
- Many countries have adopted population-based screening methods. Screening is the term used for –detection of diseases when it has not caused any symptom. People are routinely screened for breast cancers, cervical cancer, and colon cancers after they reach a particular age.
- Availability of better diagnostic modalities helping to diagnose cases that went previously undiagnosed. For example, an ultrasound of abdomen might small liver tumor which can now be picked up on CT scan. Also, more and more people have access to specialized care contributing to more
- Most importantly, due to internet and better means of communication, world is more connected- so everybody knows what is happening everywhere else. From cancer survivors to hospitals showing their data, we now know all the corners where cancers are happening.
So these are the factors that show that cancer is on the rise. But what we are keen to know is there rise in cancer incidence due to risk factors.
Lifestyles are changing. They have a strong role to play in the causation as well as prevention of cancer. Lack of exercise, lack of fiber in the diet, more processed meat or red meat consumption are implicated in causation whereas exercising five times a week for a half-hour, avoiding obesity, having diet at least two hours before bedtime are preventive among many others. This reflects on cancer trends too.
Besides, there are many risk factors that are giving rise to more cancer cases. For example, air pollution is giving rise to an increased number of lung cancer cases.
On the other side, there are certain cancers whose incidence is declining. One such cancer is CERVICAL CANCER. The majority of cancers of cervix are caused by a virus- the human papillomavirus (HPV). Now HPV infection can be prevented by vaccination. This also results in lowering of cervical cancer cases. Also, cases are decreasing due to better genital hygiene. Poor genital hygiene is a risk factor for cervical cancer. Similarly, cancers of Hepatitis B-related liver cancers are declining due to Hepatitis B vaccination.
Proceeding further, one study published in Lancet Oncology (a Scientific journal publishing cancer-related research) studied cancer incidence in India across all states from 1990 to 2016. Authors found that age-standardized incidence rate of cancer did not change substantially during this period- through the number of new cases and deaths due to cancer doubled in India from 1990 to 2016. The crude incidence and mortality from cancer increased substantially over the 26-year time period. However, there was no change in the age-standardized rates for both sexes combined, highlighting the contribution of aging and population growth to the increasing cancer burden of the country. It means, cancer incidence rate in the respective age groups has remained same, nevertheless due to more people living longer, the number of cancer cases has increased.
So to sum up, cancer cases are increasing. There are certain cancers whose numbers are decreasing. This not only depends on interplay of risk factors but also on the aging population, diagnostic facilities, and awareness in general population. But one facts needs to be emphasized again- many cancers can be prevented by lifestyle modifications and that is the way forwards in reducing cancer incidence.
Reference: The burden of cancers and their variations across the states of India: the Global Burden of Disease Study 1990-2016. India State-Level Disease Burden Initiative Cancer Collaborators. Lancet Oncol. 2018 Oct;19(10):1289-1306. doi: 10.1016/S1470- 2045(18)30447-9.