Association Between the Presence of Female-Specific Tumors and Aggressive Clinicopathological Features in Papillary Thyroid Cancer: A Retrospective Analysis of 9,822 Cases

Objective To investigate the association between the presence of female-specific tumors and aggressive clinicopathological features in papillary thyroid cancer (PTC). Methods This study retrospectively analyzed 9,822 female cases between June 2008 and December 2017. Odds ratios and corresponding 95% confidence intervals were calculated. Findings were stratified by age and body mass index (BMI) in different models. Results 1443/9822 (14.7%) patients with PTC had a female-specific tumor. Presence of a benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter (adjusted OR = 1.446, 95% CI 1.136–1.840, P = 0.003), but a protective factor against extrathyroidal extension of PTC (adjusted OR = 0.650, 95%CI 0.500–0.845, P = 0.001). Presence of a benign uterine mass was an independent risk factor for multifocal PTC (adjusted OR = 1.305, 95%CI 1.113–1.531, P = 0.001). Analyses stratified by age and BMI revealed the presence of a benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter in patients aged <36 years (adjusted OR = 1.711, 95% CI 1.063–2.754, P = 0.027), and a protective factor against extrathyroidal extension of PTC in patients aged ≥36 - <42 years (OR adjusted = 0.533, 95% CI 0.302–0.941, P = 0.030) or with a BMI ≥ 23.4 kg/m2 (BMI ≥ 23.4 to < 25.7 kg/m2, adjusted OR = 0.441, 95% CI 0.246–0.792, P = 0.006; BMI ≥25.7 kg/m2, adjusted OR = 0.558, 95% CI 0.315–0.998, P 2 = 0.045). Presence of a benign uterine mass was an independent risk factor for multifocal PTC in patients aged ≥49 years (adjusted OR = 1.397, 95% CI 1.088–1.793, P = 0.009) or with a BMI <21.5 kg/m2 (OR adjusted = 1.745, 95% CI 1.214–2.509, P = 0.003). Conclusion The presence of a benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter and a protective factor against extrathyroidal extension of PTC, while the presence of a benign uterine mass was an independent risk factor for multifocal PTC. Data from this study may help surgeons propose more personalized treatment plans when encountering patients with PTC and female-specific benign tumors.


INTRODUCTION
Evidence suggests that less women than men are affected by cancer. The National Cancer Institute estimates that one in three women and one in two men will be diagnosed with cancer during their lifetime, and women are more likely to survive cancer than men (1).
Despite this, the prevalence of thyroid cancer is higher in women than men (2)(3)(4)(5)(6), possibly due to the effects of endogenous female sex hormones, mood, stress, and genetic factors. Specifically, in vitro experiments show that estrogens promote the proliferation and invasion of thyroid cancer cell lines. Clinical data confirm a role for estrogen in the incidence of thyroid cancer (7)(8)(9)(10)(11)(12), suggesting breast cancer and thyroid cancer share a common etiology (13). In one study, women with a history of breast cancer were 1.55 times more likely to develop thyroid cancer as a secondary malignancy compared to women with no history of breast cancer, while women with a history of thyroid cancer were 1.18 time more likely to develop breast cancer as a secondary malignancy compared to women with no history of thyroid cancer (14). These data imply that women with a history of breast or thyroid cancer should adhere to the appropriate guidelines for prevention of and screening for secondary malignancies during follow-up of their primary cancer.
The presence of female-specific tumors has also been associated with the incidence of thyroid lesions (15,16). Benign breast (HR = 1.47, 95% CI 1.09-1.99) (17) and uterine (HR = 1.72, 95% CI 1.18-2.50) (13) masses may increase the risk of thyroid cancer. However, few reports have described the role of female-specific tumors in the progression of thyroid cancer.
The objective of this study was to investigate the association between the presence of female-specific tumors and aggressive clinicopathological features in papillary thyroid cancer (PTC). Understanding the molecular mechanisms responsible for sexbias differences in thyroid cancer progression may improve the management of patients with thyroid cancer and inform the development of personalized therapeutic strategies.

Study Design and Data Sources
This retrospective analysis used data collected from an institutional prospective web-based registry platform. The study was conducted in compliance with the Declaration of Helsinki. The Health Care Ethics Committee of the China-Japan Union Hospital of Jilin University, Changchun, China, approved the protocol (NO. 2019040806). All patients had signed informed consent.

Study Patients
Patients with PTC (age ≥ 18 years) who were treated at the Division of Thyroid Surgery of the China-Japan Union Hospital of Jilin University (Changchun, China), a high-volume university-affiliated teaching hospital, between June 2008 and December 2017 were eligible for this study. Exclusion criteria were: 1) age < 18 years; 2) underwent reoperation; 3) multiple female-specific tumors; 4) history of other cancer or subtype of thyroid cancer; 5) long-term use of drugs that might affect the levels of sex hormones; 6) missing data ( Figure 1).
Patients with PTC were classified into two groups according to the presence or absence of female-specific tumors, including benign breast masses, benign uterine masses, benign ovarian masses, breast cancer, or gynecological cancers. Benign breast masses included breast fibroadenoma, breast cysts, breast intraductal papilloma, and breast lipoma assigned a Breast Imaging Reporting and Data System (BI-RADS) 1-3 assessment on ultrasound and confirmed by longterm follow-up or biopsy (18). Benign uterine masses included uterine fibroids, uterine polyps, cervical cysts and uterine adenomyoma confirmed by ultrasound or pathology. Benign ovarian masses included ovarian cysts and mature teratoma confirmed by ultrasound or pathology. Breast cancers and gynecological cancers, including endometrial cancer, cervical cancer, and ovarian cancer were verified by postoperative paraffin pathology (Table S1).
PTC was diagnosed and characterized on postoperative paraffin pathology. Aggressive clinicopathological characteristics in PTC included a tumor diameter >1 cm, multifocal PTC, extrathyroidal extension of PTC, lymph node metastasis, T3-T4, clinical stage III or IV, and distant metastasis found on pathology or imaging in lung, bone, lung and bone combined, or other sites (19).

Statistical Analysis
Statistical analysis was performed using SPSS 22.0 for windows (SPSS, Chicago, IL, USA). Continuous data are reported as mean ± standard deviation and were compared using the t-test or analysis of variance. Categorical data are reported as percentages. and were compared with the chi-square test or Fisher's exact test. Binary logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). The independent variable was the coexistence of PTC and a female-specific tumor, and the dependent variables were the aggressive clinicopathological characteristics in PTC. Further binary logistic regression considered age or BMI as continuous variables in different models. ORs and corresponding 95% CIs were calculated to investigate the association between the presence of a benign breast mass and a primary PTC lesion > 1 cm in diameter, or extrathyroidal extension of PTC or the presence of a benign uterine mass and multifocal PTC. The subjects were divided into four categories based on quartiles of age and BMI in Table  6 and Table 7. P<0.05 was considered statistically significant.

Baseline Characteristics
A total of 12,124 female patients with PTC were identified from the institutional prospective web-based registry platform, of which 9,822 met the inclusion criteria ( Figure 1). Included patients were all female, with a mean ( Table 3).
On univariate analysis, compared to patients with PTC without a female-specific tumor, more patients with PTC and a  Table  4). Binary logistic regression showed that the presence of a benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter (adjusted OR = 1.446, 95% CI 1.136-1.840, P = 0.003), but a protective factor against extrathyroidal extension of PTC (adjusted OR = 0.650, 95%CI 0.500-0.845, P = 0.001). The presence of a benign uterine mass was an independent risk factor for multifocal PTC (adjusted OR = 1.305, 95%CI 1.113-1.531, P = 0.001) ( Table 5).

Association Between Benign Breast Mass and Aggressive Clinicopathological Characteristics in PTC Stratified by Age and BMI
The presence of a benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter in patients aged <36 years (adjusted OR = 1.711, 95% CI 1.063-2.754, P = 0.027). The presence of a benign breast mass was a protective factor against extrathyroidal extension of PTC in patients aged ≥36 -<42 years (OR adjusted = 0.533, 95% CI 0.302-0.941, P = 0.030). The presence of a benign breast mass had no effect on the risk of developing a primary PTC lesion > 1 cm in diameter in patients with a BMI <21.5 ->25.7 kg/m 2 . The presence of a benign breast mass was a protective factor against extrathyroidal extension of PTC in patients with a BMI ≥ 23.4 kg/m 2 (BMI ≥ 23.4 -< 25.7 kg/m 2 , adjusted OR = 0.441, 95% CI 0.246-0.792, P = 0.006; BMI ≥25.7 kg/m 2 , adjusted OR = 0.558, 95% CI 0.315-0.998, P 2 = 0.045) ( Table 6).
The presence of a benign breast mass had no effect on the risk of developing a primary PTC lesion > 1 cm in diameter in patients aged <36 years with a BMI<21.5 kg/m 2 (adjusted OR = 1.957, 95% CI 0.937-4.087, P = 0.074). The presence of a benign breast mass was a protective factor against extrathyroidal extension of PTC in patients aged ≥36 -<42 years with a BMI ≥23.4 kg/m 2 (adjusted OR = 0.289, 95% CI 0.101-0.828, P = 0.021) (Figure 2).
The presence of a benign uterine mass had no effect on the risk of developing multifocal PTC in patients aged ≥49 years with a BMI ≤21.5 kg/m 2 (adjusted OR = 1.863, 95% CI = 0.977-3.554, P = 0.059) ( Figure 2).

DISCUSSION
This retrospective analysis of 9,822 female patients investigated the association between the presence of female-specific tumors and aggressive clinicopathological features in PTC. A benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter and a protective factor against extrathyroidal extension of PTC, while the presence of a benign uterine mass was an independent risk factor for multifocal PTC. Findings revealed that the presence of benign breast or uterine masses could influence invasive growth of PTC. Patients were stratified by age and BMI. In young female (age <36 years) patients, the presence of a benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter. Among young and middle-aged overweight/obese women (age 36-42 years; BMI ≥ 23.4 kg/m 2 ), the presence of a benign breast mass was a protective factor against extrathyroidal extension of PTC. In middle-aged (>49 years) or lean (BMI<21.5 kg/m 2 ) patients, the presence of a benign uterine mass was an independent risk factor for multifocal PTC. This study demonstrated that the presence of female-specific benign tumors influences aggressive clinicopathological features in PTC. These data have implications for PTC surveillance and treatment.
Benign breast masses are commonly found in women. The prevalence of benign breast masses in China is estimated at  The present study revealed that the presence of a benign breast mass was a risk factor for a primary PTC lesion > 1 cm in diameter in women aged < 36 years(adjusted OR = 1.711, P = 0.027), but not in 36≤Age<42 (adjusted OR = 1.545, P = 0.095), 42≤Age<49 (adjusted OR = 1.286, P = 0.314), Age≥49 (adjusted OR = 1.490, P = 0.103).We suppose that the mechanism underlying the co-occurrence of a benign breast mass and thyroid cancer may involve estrogen. Estrogen plays an important role in the incidence and progression of benign breast masses (19,22), and estrogen receptor expression is a common occurrence in thyroid tumor tissues. Vannucchi et al. proved that ERa and PR expression was found in 66.5% and 75.8% of patients respectively and was significantly correlated with larger tumor size and with a non-incidental diagnosis. A trend toward a higher prevalence of local metastases was observed in ER-and PR-expressing tumors (23). Similar to our study, the author concluded that although no impact on outcome  was found, the evaluation of ERa and PR receptor expression could add insights into the biological behavior of tumors and could modify the follow-up, particularly in fertile women affected with persistent disease. And in vitro studies show that estrogens promote the proliferation of thyroid cancer cells (24)(25)(26)(27).
Ovarian reserve begins to decline at 35 years of age, the number of ovarian follicles and the quality of oocytes decreases, and estrogen secretion is reduced (28)(29)(30). Besides, one study hypothesized that differences between young and older patients with PTC had a biological/genetic basis (31). However, they didn't find a difference in the frequency or type of somatic mutations between young and older patients, six genes (extracellular matrix protein 1 [ECM1], v-erb-2 erythroblastic leukemia viral oncogene homolog 2 [ERBB2], urinary plasminogen activator [UPA], 6-phosphofructo-2kinase/fructose-2,6-biphosphatase 2 [PFKFB2], meis homeobox 2 [MEIS2], and carbonic anhydrase II [CA2]) had significant expression between the young and older patients. In another study, age was a protective factor of the primary PTC lesion > 1 cm (32). In present study, the presence of female-specific tumors was the risk factor for PTC lesion > 1 cm. With increasing age, this effect might be offset.
Interestingly, the presence of a benign breast mass was a protective factor against extrathyroidal extension of PTC. According to the data, age was a risk factor for extrathyroidal extension. With age, the risk of extrathyroidal extension gradually increased (adjusted OR 36≤age<42 = 1.189, adjusted OR 42≤age<49 = 1.233, adjusted OR age≥49 = 1.420). The protective effect of benign breast tumors might counteract the risk of extrathyroidal extension conducted related to age. It is clear that this could only be a hypothesis, it must be supported by clinical and experiemntal studies. And the effect that is unlikely to be explained by a mechanism involving estrogen (12,(33)(34)(35). but might be mediated by the tumor microenvironment. We speculate that in benign breast conditions, the immune system is challenged, and inflammation in the mammary gland may influence the thyroid gland to initiate a 'self-protection' mechanism, which prevents thyroid cancer invading through the capsule. Consequently, women with PTC and benign breast tumors may have larger diameter primary lesions but no extrathyroidal extension.
Stratifying patients by age and BMI demonstrated that the protective effect of benign breast masses on extrathyroidal FIGURE 2 | Influence of age and/or BMI on the association between the presence of a benign breast mass and a primary PTC lesion > 1cm in diameter or extrathyroidal extension of PTC, and the presence of a benign uterine mass and multifocal PTC. *P<0.05, **P<0.01.  (36). Benign uterine masses are commonly found in women, with an estimated prevalence of 4.5% to 68.6% (37). The prevalence of benign uterine masses is age dependent, reaching > 70% in women aged > 50 years (38)(39)(40). One previous study showed that the presence of a benign uterine mass was associated with an increased risk of thyroid cancer (HR = 1.72, 95% CI 1.18-2.50) (13); however, data describing the influence of a benign uterine mass on the progression of thyroid cancer is scarce.
The present study revealed that the presence of a benign breast mass was a risk factor for a primary PTC lesion > 1 cm in diameter in women aged < 36 years. The multifocality of PTC has been explained at the genetic level in different ways, being two hypothesis the more relevant to date: a) different foci composed by different clones with different genetic pattern; b) intrathyroidal metastatization. Some studies suggest discordant heterogeneous BRAF mutation patterns found in approximately 40% of the multifocal PTCs in adults (41). Multifocal PTCs had higher expression of mRNAs in Wnt-and pluripotency-related pathways when BRAF mutation was present (42). It is still primitive to give conclusions about the mechanisms, but these appear to be the most credible to explain the difference between multifocal and unifocal PTCs.
In addition, it was proved that programmed death-ligand 1 (PD-L1) expression was elevated in multifocal PTC tumors (43). The expression of programmed death-1 (PD-1) and its ligand PD-L1 is upregulated in uterine disease and promoted by 17beta-estradiol (44). Therefore, we speculated the presence of a benign uterine mass was an independent risk factor for multifocal PTC.
We found that there was correlation between PTC lesion > 1 cm and high BMI, younger age, high TSH and high Tg; between multifocality and high BMI, older age, high TPO-Ab, Tg-Ab; between ETE and high BMI, older age, high FT3, low TPO-Ab, high Tg, high Tg-Ab, low Tg/TSH; between lymph node metastasis and high BMI, younger age, high Tg, high Tg-Ab. When analyzing corresponding parameters, we would use related variables as covariates to adjust the OR value of aggressive clinicopathological features. Besides, Preoperative Tg levels may have an extremely limited value. They could be influenced by several factors not related to thyroid cancer, for example gland size (45). Thus, we analyzed Tg/TSH levels and found that lower Tg/TSH was a risk factor of ETE. These findings were similar to other studies (32,(45)(46)(47)(48)(49).
This research had several strengths. First, the study revealed the association between the presence of female-specific tumors and aggressive clinicopathological features in PTC. Second, it was a relatively large single-center retrospective analysis of the relationship between age, BMI, female-specific tumors and PTC. Last, all cases of thyroid cancer were confirmed by medical records, avoiding potential differential selection and recall bias.
This study was assoictaed with several limitations. First, it addresses an evidence gapis there an etiologic link between benign tumors and aggressive clinicopathological features in PTC. The study used a large sample size to fill this evidnce gap, but the precise mechanism underlying the co-occurrence of a benign breast/uterine mass and thyroid cancer has yet to be clearly defined. Second, as the study had a retrospective design without follow-up data, the impact on prognosis is unknown. Third, age of diagnosis of female-specific tumors and PTC were not confirmed; therefore, cause and effect cannot be established. Last, women with small benign tumors that were undetected may have been included in the analysis. Large-scale randomized controlled studies are warranted to provide further clarity to the influence of female-specific tumors on aggressive clinicopathological features in PTC.
In conclusion, this study retrospectively analyzed data collected from patients with PTC and a female-specific tumor in a single institutional database to reveal the association between the presence of a female-specific tumor and PTC proliferation and invasion. Findings showed the presence of a benign breast mass was an independent risk factor for a primary PTC lesion > 1 cm in diameter and a protective factor against extrathyroidal extension of PTC, while the presence of a benign uterine mass was an independent risk factor for multifocal PTC. The underlying mechanisms may be mediated by estrogen. Data from this study may help surgeons propose more personalized treatment plans when encountering patients with PTC and female-specific tumors.

DATA AVAILABILITY STATEMENT
The data sets generated and/or analyzed during the current study are not publicly available to protect patient privacy but are available from the corresponding author on reasonable request. Requests to access the data sets should be directed to HS, s_h@jlu.edu.cn.

ETHICS STATEMENT
This study was approved by the Health Care Ethics Committee of the China-Japan Union Hospital of Jilin University (no. 2019040806). The patients/participants provided their written informed consent to participate in this study.

AUTHOR CONTRIBUTIONS
Conception/design: HS and JZ. Collection and assembly of data: JZ, DZ, LNZ, NL, and GX. Data analysis and interpretation: JZ and LZ. Manuscript writing: JZ and GD. Final approval of manuscript: JZ, LZ, GD, DZ, LNZ, NL, GX, and HS. All authors contributed to the article and approved the submitted version.