2017 Section 7 Green Book

Surgery Volume 151, Number 6

Lang et al

Table II. A bivariable comparison of demographics, type of second primary malignancies, histology of thyroid carcinoma, and TNM stages between those who did and did not receive radioiodine ablation RAI + group ( n = 643) RAI group ( n = 252) P value * Median age of DTC diagnosis 47.5 (19.3–88.8) 44.0 (7.1–90.6) < .001 Age of DTC by groups, y .002 < 30 118 (18.4) 66 (26.2) 30–49 280 (43.5) 118 (46.8) $ 50 245 (38.1) 68 (27.0) Sex (male/female) 133/510 41/211 .133 Period of DTC diagnosis < .001 Before 1980 72 (11.2) 42 (16.7) 1980–1999 271 (42.1) 77 (30.6) After 2000 300 (46.7) 133 (52.8) Tumor size of DTC, cm 3.0 (0.1–11.0) 2.0 (0.1–7.0) < .001 Histological type of DTC .111 Papillary 505 (78.5) 190 (75.6) Follicular 138 (21.5) 62 (24.6) Stage of DTC by TNM < .001 I 377 (58.6) 209 (82.9) II 45 (7.0) 14 (5.6) III 121 (18.8) 15 (6.0) IV 100 (15.6) 14 (5.6) Type/site of NSPM y All sites 56 (8.7) 8 (3.2) .004 Breast 13 (2.0) 2 (0.8) .120 Colon 9 (1.4) 1 (0.4) .468 Lung 4 (0.6) 1 (0.4) 1.000 Liver 3 (0.5) 1 (0.4) 1.000 Corpus uteri 3 (0.5) 1 (0.4) 1.000 Stomach 3 (0.5) 0 (0.0) .567 Non-Hodgkin lymphoma 3 (0.5) 0 (0.0) .567 Rectum 2 (0.3) 1 (0.4) 1.000 Cervix 2 (0.3) 1 (0.4) 1.000 * P values were generated by using bivariable tests including v 2 , Fisher exact, and Mann–Whitney U tests wherever appropriate. y Only nonsynchronous second primary malignancy with a total number $ 3 was listed. DTC , Differentiated thyroid carcinoma; NSPM , nonsynchronous second primary malignancy; TNM , American Joint Cancer Committee/Union Interna- tionale Contre le Cancer tumor-nodes-metastasis staging system, 6th edition.

the American Joint Cancer Committee/Union Internationale Contre le Cancer tumor-node- metastasis staging system, 6th edition classification already incorporated tumor size. The following var- iables were entered in the final model: age groups, sex, period of DTC diagnosis, cumulative RAI activ- ity, and stage of DTC. Variables that were signifi- cantly associated with an increased risk of NSPM were cumulative RAI activity equaled from 3.0 to 8.9 GBq (RR, 2.777; 95% CI, 1.079–7.145; P = .034). Cumulative RAI activity of > 9.0 GBq was not significantly associated with risk of NSPM (RR, 3.149; 95% CI, 0.645–12.816; P = .131). In this cohort, the total person-years of observa- tion at risk were 10,414. After a median follow-up of 93.5 months (range, 23.4–570.8), 62 (6.9%) pa- tients developed 1 NSPM and 2 (0.2%) patients developed 2 NSPMs (ie, 2 separate primary

malignancies > 12 months after DTC). Overall, 64 patients with NSPM were observed (15 males and 49 females). The median latency period from DTC to NSPM was 189.5 months (range, 22.8–531.1). A total of 15 of 64 (23.4%) patients developed NSPM in the 5 years of follow-up. The median (range) age of NSPM was 65.6 (23.0–95.5) years old. None had known hereditary or familial cancer syndromes. In males, the 3 most common types/sites for NSPM (in descending order of frequency) were colon ( n = 3), prostate ( n = 3), and liver ( n = 2). In females, the 3 commonest types or sites of NSPM (in descending order of frequency) were breast ( n = 13), colon ( n = 7), and uterus ( n = 4). Table IV shows the observed and expected number of cases and SIRs of NSPM in the RAI + and RAI groups for males, females, and both sexes. When compared to the incidence rate in the general population, after adjusting for age

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