Pregnancy has no significant impact on the prognosis of differentiated thyroid cancer

Thyroid cancer and pregnancy: a systematic ten-year-review

Background

Thyroid cancer is the second most common malignancy during pregnancy, especially the well-differentiated thyroid cancer (well-DTC). Therefore, complex medical and social dilemmas arise, dealing with which requires deep knowledge of the nature and characteristics of the disease and pregnancy as a whole. The purpose of this review is to present the diagnostic and therapeutic strategies of thyroid cancer during pregnancy and the postpartum period.

Methods

Extended review of the literature [2011-2023] was performed. Two hundred ninety-six articles were found, from which 225 were excluded due to irrelevant subjects. Seventy-one articles were assessed for eligibility, from which 33 articles were cohort studies and case reports and were included in the review.

Results

From the 33 included studies, 18 were retrospective cohort studies, 1 was cohort study, 2 were case control studies, 1 was meta-analysis and 11 were case reports. The primary endpoints of these studies refer to the progression and recurrence of DTC during pregnancy, the prevalence of thyroid cancer in pregnancy and the most appropriate time for surgical intervention.

Conclusions

The majority of the studies agree that well-differentiated tumors with mild clinical and imaging characteristics do not require immediate surgical treatment, but mere monitoring. Surgery can be delayed after childbirth. In contrast, tumors with aggressive behavior as well as non-differentiated ones, require immediate surgery because delay under these circumstances can dramatically reduce survival rates. Finally, a history of thyroid cancer does not seem to affect future deliveries, on condition that no residual disease exists at the onset of pregnancy.

Pregnancy and the disease recurrence of patients previously treated for differentiated thyroid cancer: A systematic review and meta analysis

BACKGROUND

Differentiated thyroid cancer (DTC) is commonly diagnosed in women of child-bearing age, but whether pregnancy influences the prognosis of DTC remains controversial. This study aimed to summarize existing evidence regarding the association of pregnancy with recurrence risk in patients previously treated for DTC.

METHODS

We searched PubMed, Embase, Web of Science, Cochrane, and Scopus based on the prespecified protocol registered at PROSPERO (CRD42022367896). After study selection, two researchers independently extracted data from the included studies. For quantitative data synthesis, we used random-effects meta-analysis models to pool the proportion of recurrence (for pregnant women only) and odds ratio (OR; comparing the risk of recurrence between the pregnancy group and the nonpregnancy group), respectively. Then we conducted subgroup analyses to explore whether risk of recurrence differed by response to therapy status or duration of follow-up time. We also assessed quality of the included studies.

RESULTS

A total of ten studies were included. The sample size ranged from 8 to 235, with participants' age at pregnancy or delivery ranging from 28 to 35 years. The follow-up time varied from 0.1 to 36.0 years. The pooled proportion of recurrence in all pregnant patients was 0.13 (95% confidence intervals [CI]: 0.06-0.25; I2 : 0.58). Among six included studies reporting response to therapy status before pregnancy, we observed a trend for increasingly higher risk of recurrence from excellent, indeterminate, and biochemically incomplete to structurally incomplete response to therapy ( Ptrend <0.05). The pooled risk of recurrence in the pregnancy group showed no evidence of a significant difference from that in the nonpregnancy group (OR: 0.75; 95% CI: 0.45-1.23; I2 : 0). The difference in follow-up time (below/above five years) was not associated with either the proportion of recurrence in all pregnant patients ( P >0.05) or the OR of recurrence in studies with a comparison group ( P >0.05). Two included studies that focused on patients with distant metastasis also did not show a significant difference in disease recurrence between pregnancy and nonpregnancy groups (OR: 0.51 [95% CI: 0.14-1.87; I2 : 59%]).

CONCLUSION

In general, pregnancy appears to have a minimal association with the disease recurrence of DTC with initial treatment. Clinicians should pay more attention to progression of DTC among pregnant women with biochemical and/or structural persistence.

REGISTRATION

PROSPERO, https://www.crd.york.ac.uk/PROSPERO/ ; No. CRD42022367896.