Daily sunscreen use reduces skin cancer risk
Daily use of sunscreen with Sun Protection Factor (SPF) of 30 or more has been proven to reduce the risk of skin cancer and melanoma.
Skin cancer is the most commonly diagnosed cancer and about 90 percent of these skin cancers are caused by exposure to the sun’s ultraviolet (UV) rays.
However, regular use of sunscreen with a SPF of 15 or higher reduces the risk of developing skin cancer by 40 percent.
SPF indicates how long UV rays would take to cause a sunburn. For example, an SPF of 15 would protect from the sun’s UV rays for 15 minutes.
UV rays are high-energy radiation emitted by the sun. There are two types of UV rays; around 95 percent of UV rays are UVA and 5 percent are UVB.
Different types of sunscreen offer varying degrees of protection against UV rays from the sun. Broad-spectrum sunscreens protect against both UVA and UVB rays.
UVA rays can penetrate through glass and cause skin damage. Wearing sunscreen while indoors can protect from skin damage from UVA rays that penetrate through glass.
UVB rays are higher energy than UVA rays and are responsible for producing sunburn. The higher energy rays can also cause DNA mutations in human cells, which can progress to cancer.
Dr. Steven Q. Wang, director of Dermatologic Surgery and Dermatology at Memorial Sloan Kettering Cancer Center, said using sunscreens with SPF 30 or more can protect from up to 3 percent of UVB rays.
Even though they form a small percentage of the sun’s overall emitted UV rays, UVB rays are responsible for the majority of skin cancer formation.
The sun’s UV rays carry high-energy radiation that can mutate and damage DNA. An accumulation of DNA damage can adversely affect the cell’s growth cycle, leading to uncontrolled cell growth, which may progress to cancer.
According to the American Cancer Society, the number of new invasive melanoma cases diagnosed annually increased by 44 percent from 2011 to 2021.
The sun’s rays consist of 500 additional UVA rays that are not only responsible for skin cancer but also photoaging, which is premature aging of the skin due to sun damage. This can lead to skin pigmentary and texture changes as well as wrinkle formation.
Overexposure of unprotected skin to the sun’s UV rays leads to an increase in the production of abnormal elastin. This causes incorrectly rebuilt skin, leading to wrinkles and leathery skin.
From a cosmetic standpoint, leathery skin indicates premature aging of the skin and can later lead to early wrinkle formation.
“It's okay to have fun in the sun, as long as you are sun smart," said Dr. Joshua Zeichner, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital.
Dermatologists recommend that anyone over the age of six months should apply sunscreen for protection both indoors and outdoors, as not using sunscreen exposes the skin to the harmful UV rays from the sun.
"Starting off with a higher SPF to begin with is like a safety net and ensures that you'll get the highest level of protection for the longest period of time," Zeichner said.
