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Treatment is rarely the only cause of a second cancer, and in adults it is usually not the main one. Smoking is the clearest example: after chest radiotherapy for Hodgkin lymphoma, the risks from tobacco and from treatment appeared to multiply rather than add, which makes stopping smoking the largest single lever a survivor has over this particular risk.
What is done about it. Stopping smoking, with help rather than alone, because that is where the measured interaction is largest. Telling the oncology team about cancers in close relatives, because an inherited predisposition changes both the screening offered and the treatment chosen. And continuing with the ordinary population screening programmes, which survivors are more likely to drop out of, not less.
Smoking, measured against treatment. Within a population-based cohort of 19,046 people treated for Hodgkin's disease between 1965 and 1994, a case-control study compared 222 who developed lung cancer with 444 matched controls, using cumulative drug amounts, the radiation dose at the exact place in the lung where the cancer arose, and tobacco history. Alkylating agents without radiotherapy carried a relative risk of 4.2 (95% CI 2.1 to 8.8); a radiation dose of 5 Gy or more without alkylating agents carried 5.9 (2.7 to 13.5); both rose with dose (P for trend < .001). Risk after alkylating agents and radiotherapy together "was as expected if individual excess risks were summed". Tobacco use increased lung cancer risk more than twentyfold, and the authors state that "risks from smoking appeared to multiply risks from treatment". The authors also warn that the precise estimates "should be interpreted cautiously, given the possible residual and enhancing effects of tobacco", which is the honest caveat on their own finding.
Age. Two opposite effects run at once. Older age at treatment lowers the relative risk from radiotherapy, because there is less time for a radiation-induced cancer to appear and more competing causes of death; the SEER analysis of 647,672 survivors found relative risk decreasing with increasing age at diagnosis. But older age raises the background rate of every cancer, so the absolute number of second cancers in a survivor cohort is still dominated by people in their sixties and seventies. A young survivor has the higher multiple of a small number; an older survivor the smaller multiple of a large one.
Inherited predisposition. Family history is measurable as a risk factor for a second cancer in its own right. Using a population-based database of 41,181 people with Hodgkin lymphoma (7,476), non-Hodgkin lymphoma (25,941) or chronic lymphocytic leukaemia (7,764) and cancer diagnoses in 110,862 first-degree relatives, people with Hodgkin lymphoma and a family history of any cancer had a relative risk of breast cancer of 1.81 (95% CI 1.04 to 3.16) compared with those without. Among people with chronic lymphocytic leukaemia, a positive family history carried raised risks of bladder (3.53, 1.31 to 9.55) and prostate cancer (2.15, 1.17 to 3.94). The associations for non-Hodgkin lymphoma were not statistically significant. A specific inherited syndrome changes this further: a person with a pathogenic TP53 variant is both more likely to develop a radiation-induced cancer and eligible for a different screening protocol, which is why the NHS very high risk breast programme screens that group with magnetic resonance imaging alone and states that mammography is contraindicated for them.
What the evidence does not support. In the joint analysis of childhood cancer survivors cited on the frailty and late-effects record on this front, treatment and genetic predisposition accounted for most of the attributable risk of a subsequent neoplasm, and lifestyle factors contributed negligibly. Diet and exercise have the strongest evidence in survivorship for fitness, function and in colon cancer for survival; they are not where the evidence for preventing a second cancer lies. Smoking is the exception, and it is a large one.
Showing the technology this term belongs to: Survivorship care and late-effects surveillance.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Screening survivors: where the UK, American and European answers differ, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Screening survivors: where the UK, American and European answers differ, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers.
Shares Second cancers after radiotherapy, Lung cancer after chest radiotherapy and after alkylating chemotherapy, Second cancers after treatment: what the risk is, and what is done about it, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Screening survivors: where the UK, American and European answers differ, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Screening survivors: where the UK, American and European answers differ, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Screening survivors: where the UK, American and European answers differ, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Screening survivors: where the UK, American and European answers differ, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Secondary malignancy (therapy-related cancer), Survivorship care and late-effects surveillance and the tags rejuvenation, survivorship, second-cancers.