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A second cancer is a brand new cancer, not the first one coming back. Most are found by the ordinary routes, and some have a screening programme attached, which is the part worth asking about by name. The risk comes from three things that add together: the treatment, the thing that caused the first cancer and has not gone away, and simply having lived longer.
What is done about it. Three things, in order of how much they change. A treatment summary that lists what you were given, at what dose, to what part of the body, because no screening decision can be made without it. Enrolment in any screening programme your exposures qualify you for, which in the United Kingdom means the very high risk breast programme for women irradiated to the chest when young. And continued attention to the ordinary risks, because in adults treated as adults most second cancers are not caused by the treatment.
How common. In the SEER registries, 2,116,163 adults diagnosed between 1992 and 2008 with one of the ten commonest cancers were followed; 170,865 of them, 8.1 per cent, developed a second primary malignancy. Survivors of bladder cancer had the highest risk. Adjusting for age, race, grade, stage, marital status, education and income, a history of non-Hodgkin lymphoma predicted the highest risk of a second cancer (hazard ratios 2.70 in men and 2.88 in women), followed by bladder cancer (1.88 and 1.66). Among people who had two incident cancers, 13 per cent died of the first and 55 per cent of the second; lung cancer was the cause of death in 12 per cent. The authors' own summary sentence is that "nearly 1 in 12 patients diagnosed with a common cancer developed a second malignancy, the most common of which was lung cancer".
How much of it is the treatment. Less than most people assume, in adults. Across nine SEER registries, 647,672 adults diagnosed between 1973 and 2002 with one of fifteen cancers routinely treated with radiotherapy were followed for a mean of 12 years; 60,271 of them, 9 per cent, developed a second solid cancer. Comparing those who had radiotherapy with those who did not, the relative risk exceeded 1 for every first-cancer site, from 1.08 (95% CI 0.79 to 1.46) after cancers of the eye and orbit to 1.43 (1.13 to 1.84) after cancer of the testis. The excess amounted to 3,266 second solid cancers (2,862 to 3,670), which is 8 per cent (7 to 9) of all second solid cancers in people who had radiotherapy, or five excess cancers per 1,000 people treated with radiotherapy by fifteen years. The paper's conclusion is worth reading exactly: "A relatively small proportion of second cancers are related to radiotherapy in adults, suggesting that most are due to other factors, such as lifestyle or genetics."
Why the childhood numbers are so much larger, and do not transfer. A child irradiated at eight has seventy years in which a radiation-induced cancer can appear, growing tissue that is more radiosensitive, and no competing causes of death. An adult of sixty-five has none of those things. The childhood-cancer cohorts are covered elsewhere on this front; their attributable fractions, which reach 92 per cent for meningioma, are theirs and not transferable to a person treated at sixty.
The three mechanisms, each with its own record here. Cytotoxic drugs that damage DNA in blood stem cells, producing therapy-related myeloid neoplasms. Radiation, producing solid cancers in or at the edge of the treated field, decades later. And shared cause, where the smoking, alcohol, virus or inherited variant that produced the first cancer is still present and produces a second. These behave differently, appear at different times, and call for different answers.
What this is not. Not the first cancer coming back, which is recurrence; not the first cancer spreading, which is metastasis. A record below sets out the difference, because getting it wrong changes everything about what the news means.
Showing the technology this term belongs to: Survivorship care and late-effects surveillance.
Shares From a clone in the blood to a leukaemia: what is known, and what is done, Frailty and late effects in survivors, Second cancers after radiotherapy, Alkylating agents and therapy-related myeloid neoplasms and the tags rejuvenation, survivorship, second-cancers.
Shares Survivorship care and late-effects surveillance, Late effects and survivorship toxicity, Survivorship and late effects are neglected and the tags rejuvenation, survivorship, late-effects.
Shares Late effects and survivorship toxicity, Survivorship and late effects are neglected and the tags rejuvenation, survivorship, late-effects.
Shares Frailty and late effects in survivors, Secondary malignancy (therapy-related cancer), Survivorship care and late-effects surveillance, Late effects and survivorship toxicity and the tags rejuvenation, survivorship, late-effects.
Shares Frailty and late effects in survivors, Second cancers after radiotherapy, Late effects and survivorship toxicity, Survivorship and late effects are neglected and the tags rejuvenation, survivorship, late-effects.
Shares Survivorship care and late-effects surveillance, Late effects and survivorship toxicity, The hardest cancers are found late, Survivorship and late effects are neglected and the tags rejuvenation, survivorship, late-effects.
Shares Frailty and late effects in survivors, Late effects and survivorship toxicity, Survivorship and late effects are neglected and the tags rejuvenation, survivorship, late-effects.
Shares Survivorship care and late-effects surveillance, Late effects and survivorship toxicity, Survivorship and late effects are neglected and the tags rejuvenation, survivorship, late-effects.