Smoking, Obesity, and the Risk for Second Cancers

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Updated March 2022

If we needed more proof that smoking and obesity can cause serious bodily harm, here’s the latest: Survivors of cancers caused by these two factors have a higher risk of developing a second type of cancer.

Researchers from the American Cancer Society (ACS) in Atlanta analyzed data from a dozen Surveillance, Epidemiology, and End Result registries, looking at the health outcomes of 1.53 million people who had survived at least five years after being diagnosed with a first cancer. They found that about 10% of those were eventually diagnosed with a subsequent cancer. Smoking-related and obesity-related subsequent cancers (called second primary cancers) accounted for an outsized number of that 10%.

Smoking-related subsequent primary cancers (referred to as SPCs) made up 45% of all such diagnoses and deaths. In contrast, obesity-related subsequent cancer deaths could be blamed for about a quarter. Zoukaa Sargi, M.D., a head and neck surgeon at Sylvester Comprehensive Cancer Center, who specializes in head and neck tumors, wasn’t surprised. “We see it all the time,” he says. “All tissues of the body are exposed to the effects of smoking, not just the mouth, tongue and lungs.”

The risk of developing a second primary cancer varied between men and women cancer survivors. Compared to the general population, men had an 11% higher risk of developing and a 45% higher risk of dying from a second cancer after surviving their first bout. Women had a 10% higher risk of development and a 33% higher risk of dying from SPCs.

This was true for 18 of 30 primary cancer types diagnosed in men and for 21 of the 31 primary cancers in women. The primary cancers that proved to have the highest risk were also different according to sex, but laryngeal cancer was found to be the riskiest of primary cancers for both men and women.

Risk for second cancersDr. Sargi says that patients with laryngeal cancer are usually smokers. Many are also alcohol drinkers. Both habits can be detrimental to health, and the association of both “creates a synergistic effect when it comes to the risk of cancer development.”

“We follow those patients for the rest of their lives,” he explains. “We know that patients with smoking-related head and neck cancers are at a higher risk of developing other cancers.”

ACS researchers also found that male survivors of Hodgkin’s lymphoma were more likely to develop a second cancer while gallbladder cancer survivors were more likely to die from an SPC. For women, esophageal cancer was the second riskiest primary cancer after laryngeal.

Other smoking-related cancers that comprised a significant proportion of SPCs include lung, urinary bladder, oral cavity/pharynx, colorectal, pancreatic, uterine corpus, and liver.

Lung cancer alone accounted for almost a third of all deaths from subsequent primary cancers.

The chance of developing a second primary cancer was similarly risky for survivors of obesity-related cancers. Among the most common: colorectum and pancreas.

This data confirms what clinicians have long observed, and it will prove particularly useful for primary care doctors, Dr. Sargi says. They usually perform the routine care of cancer survivors once patients transition out of a specialty practice at the five-year survival mark.

The study also supports the importance of mitigating SPCs with continuous medical monitoring. Regular screenings – mammogram, pap smear, colonoscopy, blood tests, annual physicals, and CT scans for smokers — can catch tumors early, when they’re more likely to respond to treatment, Dr. Sargi says.

It should also reinforce attention on the importance of a healthy lifestyle, including exercise, healthy eating, smoking cessation, and weight management.

“We see the first diagnosis of cancer as a teachable moment,” Dr. Sargi adds. “This is when we can explain to the patients that they may not be able to do much about genetic risk factors, but they can avoid the known lifestyle and environmental factors moving forward. A healthy lifestyle reduces risk and improves the quality of life.”


Ana Veciana-Suarez, Guest Columnist

Ana is a regular contributor to the University of Miami Health System. She is a renowned journalist and author who has worked at The Miami Herald, The Miami News, and The Palm Beach Post. Visit her website at or follow @AnaVeciana on Twitter.




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