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The thyroid is among the most radiation-sensitive tissues there is, and neck or upper chest radiotherapy raises the risk of thyroid cancer for decades. Whether to look for it is genuinely unsettled: the international guideline panel compared ultrasound against feeling the neck, found neither better, and wrote a decision aid instead of a recommendation.
What is offered. An annual thyroid function blood test after neck or upper chest radiotherapy, which is for underactive thyroid rather than for cancer and is far more often abnormal. For thyroid cancer itself, what is offered differs by country and by clinic, and the honest answer is that the question has not been settled.
The risk, where it has been measured in adults. In the meta-analysis of 22 population-based studies of women treated for breast cancer, the standardised incidence ratio for thyroid cancer in irradiated women at fifteen years or more was 3.15; in unirradiated women the overall figure was 1.21 with no remaining excess beyond ten years. The earlier meta-analysis of 13 studies found no significant association between radiotherapy and second thyroid cancer at five years or more, so two analyses by the same authors differ depending on how long the women were followed. That disagreement is the state of the evidence, not a mistake in reading it.
Why looking is harder than it sounds. Thyroid cancer is the clearest example in oncology of a disease that can be found more often without anyone living longer. Ultrasound of an irradiated neck finds small nodules in a large fraction of people; most are not cancer, and many of the cancers found would never have caused symptoms. Against that sits the fact that a differentiated thyroid cancer found late is harder to treat than one found early.
What the guideline actually says. The International Late Effects of Childhood Cancer Guideline Harmonization Group, with the PanCareSurFup Consortium, assembled 33 experts to settle this for survivors of childhood, adolescent and young adult cancer. Their finding was that of the two available surveillance strategies, thyroid ultrasound and neck palpation, "neither was shown to be superior". Rather than recommend one, they produced a decision aid to guide the clinician in counselling the survivor, and the recommendations "highlight the need for shared decision making regarding whether to undergo surveillance for DTC and in the choice of surveillance modality". A guideline that declines to recommend, and says why, is more useful than one that picks a side it cannot defend.
What this means for an adult treated as an adult. That guideline covers people treated as children, adolescents or young adults. For someone irradiated to the neck at fifty, no equivalent guideline exists, the risk is lower because age at exposure lowers it, and the default in most health systems is no thyroid cancer surveillance at all. A lump in the neck, a change in the voice, or difficulty swallowing are the reasons to be examined, in a survivor as in anyone else.
Showing the technology this term belongs to: Ultrasound.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Radiotherapy and second cancers: field, dose and age at exposure, Screening survivors: where the UK, American and European answers differ and the tags rejuvenation, survivorship, second-cancers, radiotherapy.
Shares No randomised trial shows that any survivorship screening programme reduces death, Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Radiotherapy and second cancers: field, dose and age at exposure and the tags rejuvenation, survivorship, second-cancers, radiotherapy, screening.
Shares No randomised trial shows that any survivorship screening programme reduces death, Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Radiotherapy and second cancers: field, dose and age at exposure and the tags rejuvenation, survivorship, second-cancers, radiotherapy, screening.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Radiotherapy and second cancers: field, dose and age at exposure, Screening survivors: where the UK, American and European answers differ and the tags rejuvenation, survivorship, second-cancers, radiotherapy, screening.
Shares No randomised trial shows that any survivorship screening programme reduces death, Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Radiotherapy and second cancers: field, dose and age at exposure and the tags rejuvenation, survivorship, second-cancers, radiotherapy.
Shares No randomised trial shows that any survivorship screening programme reduces death, 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 and the tags rejuvenation, survivorship, second-cancers, screening.
Shares Second cancers after radiotherapy, Second cancers after treatment: what the risk is, and what is done about it, Radiotherapy and second cancers: field, dose and age at exposure, Secondary malignancy (therapy-related cancer) and the tags rejuvenation, survivorship, second-cancers, radiotherapy.
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.