Artigo português sobre cancros potencialmente induzidos pela exposição a radiação publicado em revista científica americana

Duas médicas do IPOLFG reviram o processo clínico de mais de 2.000 de doentes com cancro diferenciado da tiróide e avaliaram o risco de desenvolverem outras neoplasias primárias. Verificaram que actividades acumuladas de Iodo-131 acima dos 200mCi podem ter influência. A administração de actividades mais baixas, parece não ter riscos associados. Este cancro é o mais frequente em endocrinologia e prevê-se que a sua incidência aumente significativamente. O radioiodo é utilizado há mais de 70 anos e continua a ser recomendado após a cirurgia, pois melhora a sobrevivência, auxilia no estadiamento e facilita o seguimento destes doentes. O artigo foi publicado em Junho/2017 numa conceituada revista americana da área e alerta para o risco das actividades altas (utilizadas em casos clínicos específicos e nos quais deve ser avaliado o risco-benefício junto dos profissionais competentes).

Autores e Afiliações:

Margarida Silva-Vieira,^1,* Sofia Carrilho Vaz,^2,* Susana Esteves,³ Teresa C. Ferreira,² Edward Limbert,^1,4 Lucília Salgado,² Valeriano Leite^1,5

¹Serviço de Endocrinologia, Instituto Português de Oncologia de Lisboa Francisco Gentil E.P.E, Lisboa, Portugal

²Serviço de Medicina Nuclear, Instituto Português de Oncologia de Lisboa Francisco Gentil E.P.E, Lisboa, Portugal

³Unidade de Investigação Clinica, Instituto Português de Oncologia de Lisboa Francisco Gentil E.P.E, Lisboa, Portugal

⁴Registo Oncológico Regional Sul, Lisboa, Portugal

⁵Faculdade de Ciências Médicas, Universidade nova de Lisboa, Lisboa, Portugal.

*estes autores contribuíram de igual forma para este trabalho

Abstract:

Background: Well-differentiated thyroid cancer (WDTC) is the most common endocrine neoplasia, and its incidence is rising. Studies have reported an increased risk of second primary cancer (SPC) in WDTC survivors, but its relationship with radioiodine treatment (RAIT) and other risk factors remains controversial. This study evaluated whether RAIT is an independent risk factor for SPC in WDTC patients.

Methods: This was a retrospective single-center study. A total of 2031 patients with WDTC diagnosed between 1998 and 2009, treated and followed at the authors' tertiary cancer center, were included.

Results: The median age of patients was 48 years (range 5–90 years); 83% were women and 77% underwent RAIT. The median follow-up was 8.8 years (range 5.0–17.0 years). A total of 130 SPC were diagnosed: 108/1570 (6.9%) received RAIT (RAIT+) and 22/461 (4.8%) did not (RAIT–). The most common SPC was breast cancer (31%), followed by genitourinary and gastrointestinal cancer (18% each). The 10-year cumulative incidence of SPC was 8.2% in RAIT+ and 4.5% in RAIT–. The absolute risk increase in the RAIT+ group versus the RAIT– group at 10 years of follow-up was 0.039 [confidence interval (CI) 0.011–0.067] per patient-year. The number needed to harm (NNH) was 25.6 [CI 15.0–87.2], indicating that on average during a 10-year follow-up period, there is one additional case of SPC for every 26 patients receiving RAIT. When controlling for age, sex, and familial and personal histories of cancer, there was an 84% increase in the risk of SPC in the RAIT+ group compared to the RAIT– group (p = 0.026; relative risk = 1.84 [CI 1.02–3.31]). There was an association between SPC incidence and total cumulative activity administered, which was statistically significant >200 mCi. The incidence of SPC was higher in both the WDCT and the RAIT+ cohorts compared to the general population (standardized incidence ratios = 1.32 and 1.40, respectively).

Conclusion: These results indicate that in spite of the low incidence of SPC in WDTC patients, the risk is increased after RAIT, particularly for activities >200 mCi. Thus, considering the excellent survival of patients with WDTC, clinicians need to weigh the risks and benefits of RAIT, especially in patients with low-risk thyroid cancer.

Revista:Thyroid

Link: http://online.liebertpub.com/doi/10.1089/thy.2016.0655