Page 55 - Read Online

Izkhakov et al. J Cancer Metastasis Treat 2021;7:24 https://dx.doi.org/10.20517/2394-4722.2021.24 Page 3 of 8

the end of the surveillance period. Moreover, the number of cardiovascular risk factors correlated positively
with the risk of mortality among the TC survivors, with 2-4 factors increasing the risk to a level of
significance (HR = 1.23 [1.03-1.47], 1.66 [1.38-1.99], and 2.59 [2.11-3.19], respectively).

Several studies on TC survivors who were receiving TSH suppression therapy have shown impairments in
cardiac structure [17,18] , diastolic function [19-22] , and systolic function ; an increased prevalence of AF ; and
[24]
[23]
[25]
[26]
an increased prevalence of prothrombotic condition . Contrarily, Pajamäki et al. found a 27% decreased
cardiovascular mortality risk among 901 DTC survivors in comparison to 4485 matched controls in a
Finnish population-based study during a median 18.8-year follow-up period. One of the authors’
explanations for this finding was that the lifelong follow-up of DTC survivors possibly facilitated earlier
determination and treatment of cardiovascular risk factors compared to the general population.

Cardiovascular morbidity
Several large retrospective studies on cardiovascular morbidity among TC survivors were published over the
last few years. Pajamäki et al. found an increase in the risk of any cardiovascular disease (HR = 1.16 [1.05-
[26]
[27]
1.28]) among 901 Finnish DTC survivors in comparison to matched controls. Suh et al. investigated the
incidence of coronary heart disease among 182,419 Korean TC survivors and 182,419 non-cancer controls
in a mean 4.3-year follow-up period. The TC survivors had an increased risk for coronary heart disease (HR
= 1.15 [1.1-1.22]), and it was dependent upon high-dose levothyroxine (HR = 1.47 [1.34-1.6]).

Izkhakov et al. assessed the atherosclerotic cardiovascular outcome among 5677 Israeli TC survivors in
[28]
comparison to 23,962 adults with no thyroid disease in a mean 7.6-year follow-up period. In that study, TC
survivors had an elevated risk of new atherosclerotic cardiovascular events before (HR = 1.20 [1.08-1.34])
and after (HR = 1.18 [1.05-1.33]) exclusion of patients with past cardiovascular pathology in both groups. In
addition, TC survivors who developed cardiovascular events had a higher incidence of hypertension and
hyperlipidemia.

[29]
Zoltek et al. compared cardiovascular incidence among 6900 DTC survivors to the general Swedish
population. They revealed more hospitalizations for AF (SIR = 1.66, 95%CI: 1.41-1.94), but there was no
difference in hospitalization rates between DTC survivors and the general population with regard to other
studied cardiovascular diseases.

Among people > 60 years of age, an endogenously suppressed TSH level could lead to congestive heart
[31]
[30]
failure with poor outcome . Blackburn et al. investigated the risks of aging-related diseases among 3706
TC survivors, diagnosed before and after age 40, compared to 15,587 matched cancer-free individuals from
Utah Population Database. The authors found increased risk for cardiovascular morbidity in both age
groups 1-5 years after cancer diagnosis compared to the matched cancer-free participants (HR = 1.76 [1.40-
2.21] vs. HR = 1.49 [1.38-1.6]). Survivors < 40 had a higher risk of hypertension (HR = 2.03 [1.75-2.32] vs.
HR = 1.58 [1.48-1.68]), but there was no difference in rate of congestive heart failure among both age groups
of TC survivors and the matched cancer free participants.

AF
A number of investigations found a high incidence of AF among DTC survivors. Pajamäki et al. reported
[26]
an increased risk of all types of arrhythmia (HR = 1.25 [1.06-1.48]) in association with AF (HR = 1.27 [1.06-
1.57]) among 901 Finnish DTC survivors in comparison to matched controls during a median 18.8-year
surveillance period. In a subgroup analysis, low TSH levels were linked with an increased risk of AF.
[27]
Suh et al. revealed an elevated risk for AF among TC survivors compared to controls when the dosage of