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Prevention of Cancer – 16 – Solar and other Radiation

Prevention of Cancer PART – 16

(All the articles published in past are available at

Question:  In last part, we discussed some very important points 1. Risk of colon cancer with use of antibiotics repeatedly. To avoid for simple ailments. 2. Risk of cancer with processed meat, and red meat. 3. Foods cooked at very high temperatures are in general less healthy e.g. fried foods, ultraprocessed, bakery 4. Chemicals in practically every aspect of our life. Cannot study each chemical. Better to use less of all chemicals as much as possible. E.g. packaged foods, cosmetics, pesticides, fertilizers, cleaning materials, air freshners, plastics…

I like the simple rule you gave: uncooked is safest, cooked at home is safer, cooked outside of home or packaged is least safe.

Ans: Fried foods require a special mention here. They are cooked at very high temperatures. And repeated use of same oil leads to higher level of probable carcinogenic chemicals. Foods cooked outside of home frequently use same oil several times. One important reason why home cooked food is healthier.

Que: Thank you for bringing out this very important point. Indians are particularly fond of fried food. And the quality of oil, repeated use of oil have been raised as important concerns for many years. For heart disease as well. Now what about other environmental factors, apart from chemicals?

Ans: One of the important chemicals is Radon gas. We don’t think of this typically as chemical, since it is in a gas form, it is odorless, and is produced without our control. This is an indoor gas produced over time from decay of uranium, radium. Comes from soil, rock, groundwater. Risk level is small, and about 2% of total lung cancers is possibly associated with Radon gas exposure, as per estimates in USA.

Air pollution, water pollution by various chemicals is also an important factor. Certain geographic areas have water with arsenic for example, which is a known carcinogen. Air pollution can be due to several reasons, including vehicle emission, burning of paddy in farms, construction, emission from factories…

But the next important category that we are going to talk about for Environmental factors, is Solar and other radiation.

Solar radiation is a very important risk factor for skin cancers. In white skin populations i.e. western countries, skin melatonin pigment is very low. Hence they have little protection from ultraviolet rays of sunlight. Malignant melanoma is a very important and common cancer in western countries. Squamous cell cancer and basal cell cancer of skin is also associated with exposure to UV rays from sunlight. Higher the exposure time, higher the risk. Additionally, sunburns increase risk significantly, more so if in young age up to adolescense. Artificial UV rays as in tanning bed exposure also increases risk of melanoma.

UV rays lead to genetic mutations in skin. This over several years to decades can lead to cancer.

It is important to note that prevention of skin cancer guidelines recommend avoiding strong sunlight i.e. around noon till evening. Early morning and late evening sunlight exposure is safe.

Que: Thank you for this explanation about sunlight and tanning bed exposure and risk of skin cancer. This is much less common in India in terms of incidence per population. But what about other forms of radiation you mentioned earlier?

Ans: Most well known are the atomic radiation, from nuclear bomb blast or leak from atomic plant. These strong radiation rays can damage DNA and lead to cancer. This was well studied in survivors of Hiroshima and Nagasaki bomb blasts. However fortunately these are extremely rare events.

What raises more alarm in general however is medical use of radiation i.e. xray, CT scan, PET scan etc. Sonography and MRI are safe from radiation point of view.

X rays use very small amount of radiation. But CT scan and other studies requiring longer exposure such as angiography are important. Not with few studies, but many studies done over life time deserve attention. PET scans lead to a particularly high dose of radiation. Hence their use is being restricted in follow up cases, as per most international guidelines related to cancer. In case of children, this is particularly important, and even single or few CT scans may pose an important risk over next few decades. Like all other risk factors for cancer as we have seen earlier, younger the age, higher the risk.

Radiotherapy used to treat cancer uses particularly high doses of radiation, with a limited field however. Once again, risk in children is significantly higher compared with adults. For example, radiotherapy to breast in early age increases risk of developing breast cancer at a later age. Various sarcomas are also associated with radiation therapy especially in younger age. Risk is smaller in most cases compared to its benefit in cure of cancer. Based on this knowledge however there is an emphasis in reducing use of radiotherapy in children in most modern protocols of cancer treatment.

Staff working in Radiotherapy department and Radiology department are closely monitored for exposure to radiation.

Some airports use xrays for passenger screening. Amount of radiation used in this screening is extremely small.

April 8, 2023

Dr Chirag A. Shah; M.D. Oncology/Hematology (USA), 9998084001. Diplomate American Board of Oncology and Hematology. Ahmedabad.