Effect of Pre-Existent Sarcopenia on Oncological Outcome of Advanced Thyroid Cancer Patients Treated with Tyrosine Kinase Inhibitors

Simple Summary Data regarding the effect of pre-existent sarcopenia on the oncological outcome of advanced thyroid cancer patients treated with tyrosine kinase (TKI) are still lacking. The aim of the study was to investigate the prevalence of pre-treatment sarcopenia in Caucasian patients affected by advanced thyroid carcinoma and the impact of this condition on the response to TKIs treatment. Pre-treatment sarcopenia was found in 20.7% of patients, with an increase of up to 38.5% after 12 months of TKI therapy. Pre-treatment sarcopenia significantly affected treatment outcome, emerging as the parameter that has the greatest impact on Progression Free Survival. Sarcopenia might be used as a prognostic factor of TKI treatment outcome and the prevention of this condition, ideally before starting anticancer treatment, could be the strategy to obtain a better efficacy of therapy. Abstract (1) Background: Sarcopenia is associated with poor survival and treatment outcomes in several human cancers. The aim of the study was to investigate the prevalence of sarcopenia in a cohort of 58 Caucasian patients with advanced thyroid cancer before and during TKI treatment. The impact of this condition on the outcome of patients was also evaluated. (2) Methods: Sarcopenia was evaluated using the Skeletal Muscle Index (SMI). (3) Results: Pre-treatment sarcopenia was found in 20.7% of patients and this condition significantly affected treatment outcome, emerging as the parameter that has the greatest impact on Progression Free Survival (PFS) (HR 4.29; 95% CI, 1.21–15.11, p = 0.02). A significant reduction in SMI values was observed 3 (p = 0.002) and 12 months (p < 0.0001) after TKI treatment. At a 12-month follow-up, sarcopenia prevalence increased up to 38.5%. Here, 12-month sarcopenia was predicted by a lower SMI (p = 0.029), BMI (p = 0.02) and weight (p = 0.04) and by the presence of bone metastases (p = 0.02). (4) Conclusions: This is the first study that evaluated sarcopenia prevalence and its change over time in Caucasian patients with advanced thyroid cancer under TKI therapy. Sarcopenia seems to be a prognostic factor of TKI treatment outcome, suggesting the importance of the assessment of the nutritional status and body composition in advanced thyroid cancer patients.


Introduction
Sarcopenia, malnutrition, and cancer cachexia often co-exist in patients with advanced cancer and are associated with poorer response to cancer therapy and with reduced survival [1][2][3][4][5]. It is important to recognize the differences between malnutrition, sarcopenia,

Assessments and Definitions
We evaluated in all patients the following anthropometric parameters: weight, height, and BMI. The weight (kilograms) and height (meters) were measured using a scale with an altimeter (Seca-, Hamburg, Germany). The BMI was calculated as "weight over height squared".
Radiological evaluation was performed at baseline (before treatment) and periodically (on average at 3, 6 months and thereafter annually) with computed tomography (CT) scan with contrast medium. Response to treatment was classified as Partial Response (PR), Stable Disease (SD), and Progressive Disease (PD) according to Response Evaluation Criteria in Solid Tumors (RECIST) v.1.1 [22,23]. The time from TKI administration to the first evidence of tumor progression or until death was defined as Progression-free survival (PFS). Overall Survival (OS) was considered as the time from the start date of the TKI treatment to the time of death from cancer disease. The sum of Target Lesions (TL) was calculated as the sum of diameters (longest for non-nodal lesions, short axis for nodal lesions) of all target lesions measured at baseline, according to RECIST criteria.
The PFS and OS were evaluated in a subpopulation of 23 patients ( Figure 1) all with DTC or PDTC and treated with only one TKI (lenvatinib or sorafenib), to avoid the potential bias due to different histotypes and multiple lines of TKI treatment.

Statistical Analysis
According to a preliminary descriptive analysis, quantitative variables were summarized by mean ± standard deviation, median and minimum-maximum range and qualitative variables by absolute frequencies and percentages.
The comparison of the quantitative variables was performed by t-test and Mann-Whitney test, based on normality verified by the Kolmogorov-Smirnov test, while the Chi-square test and Fisher's exact test were used to compare qualitative variables.
The repeated measures ANOVA was used to compare the value of SMI and ∆SMI% at different times (3, 6, and 12 months).
ROC (Receiver Operating Characteristic) curve analysis was performed to find the best SMI cut-off, in male and female patients, and the best BMI cut-off able to predict the presence of sarcopenia after 12 months of treatment.
Progression Free Survival and Overall Survival were assessed by Kaplan-Meier and Cox regression. Hazard ratios and their 95% confidence interval (CI) were estimated.
Stepwise Cox regression was performed, to identify factors contributing to Overall or Progression Free Survival. A p-value < 0.05 was considered statistically significant. The analyses were performed with SPSS statistics version 27.0 (IBM Corp, Armonk, NY, USA) and Stat-View version 5.0.1 for Windows (SAS Institute Inc., Cary, NC, USA). A radiologist identified, for each patient, the single axial image at the level of the third lumbar vertebrae (L3) on which both transverse processes were fully observed, including psoas, erector spinae, quadratus lumborum, transversus abdominis, external and internal obliques, and rectus abdominis. Based on these images, was obtained the Skeletal Muscle Area (SMA; the cross-sectional area of all skeletal muscles at the L3 level). SMA was measured using the attenuation thresholds of −29 to +150 Hounsfield units. The Skeletal Muscle Index (SMI) was later calculated as SMA normalized by height squared and reported as cm 2 /m 2 .
The SMI cut-off to define sarcopenia was chosen among those proposed by the most recent European consensus [14] and it refers to a population of healthy subjects from the United States [24]. According to the SMI cut-off of 34.4 cm 2 /m 2 for females and 45.4 cm 2 /m 2 for males, patients were divided into a Sarcopenia Group (SG) and a Non-Sarcopenia Group (NSG). The percentage of loss of SMI (∆SMI%) was calculated as "(baseline SMI-SMI at time x)/SMI baseline × 100", whereas the SMI, in addition to the baseline, was calculated at different times, including 3, 6, 12 months (time x) after the start of treatment. Skeletal Muscle Index and sarcopenia variations were assessed in a sub-group of 39 patients with a period of observation of at least 12 months with available clinical, biochemical, anthropometric, and radiological data at 3 and 12 months after starting TKI treatment (Figure 1).
In a subgroup of patients with available data, the Controlling Nutritional Status (CONUT) score was assessed at baseline (before starting TKI treatment) and during followup. It was defined as the sum of the following parameters, as described in the literature [25]: for serum albumin levels > 3.5, between 3.0 and 3.49, between 2.5 and 2.99 and <2.5 g/dL, 0, 2, 4, and 6 points were assigned, respectively; for serum total cholesterol levels > 180, between 140 and 179, between 100 and 139 and <100 mg/dL, 0, 1, 2, and 3 points were assigned, respectively; for serum total lymphocyte count > 1600, between 1200 and 1599, between 800 and 1199 and <800/mm 3 , 0, 1, 2, and 3 points were assigned, respectively.
The concentrations of albumin, total cholesterol, and total lymphocyte count were measured with standard colorimetric methods using the Cobas c 701/702 analyzer (Roche/Hitachi, Mannheim, Germany), obtained by fasting venous blood samples.

Statistical Analysis
According to a preliminary descriptive analysis, quantitative variables were summarized by mean ± standard deviation, median and minimum-maximum range and qualitative variables by absolute frequencies and percentages.
The comparison of the quantitative variables was performed by t-test and Mann-Whitney test, based on normality verified by the Kolmogorov-Smirnov test, while the Chi-square test and Fisher's exact test were used to compare qualitative variables.
The repeated measures ANOVA was used to compare the value of SMI and ∆SMI% at different times (3, 6, and 12 months).
ROC (Receiver Operating Characteristic) curve analysis was performed to find the best SMI cut-off, in male and female patients, and the best BMI cut-off able to predict the presence of sarcopenia after 12 months of treatment.
Progression Free Survival and Overall Survival were assessed by Kaplan-Meier and Cox regression. Hazard ratios and their 95% confidence interval (CI) were estimated. Stepwise Cox regression was performed, to identify factors contributing to Overall or Progression Free Survival. A p-value < 0.05 was considered statistically significant. The analyses were performed with SPSS statistics version 27.0 (IBM Corp, Armonk, NY, USA) and StatView version 5.0.1 for Windows (SAS Institute Inc., Cary, NC, USA).

Clinical-Pathological Features of the Whole Cohort of Patients
A total of 28 (48.3%) patients were female and 30 (51.7%) were male. The mean age at the time of TKI treatment was 67.5 ± 13.8 years (median 69 years, 30-96 years).
The performance status at baseline, according to the Eastern Cooperative Oncology Group (ECOG) scale, was 0 in 50 patients (86.2%), one in six patients (10.3%), and two in two patients (3.5%).

Baseline Sarcopenia and Response to TKI Treatment
At the last follow-up, 14 patients (24.14%) were under TKI treatment, among them 10 with the first line therapy (9/10 patients with lenvatinib and 1/10 patients with vandetanib), four patients (6.9%) were lost at follow up, 39 patients (67.24%) died due to thyroid disease or for other reasons, and anticancer treatment was withdrawn in one patient (1.72%). The duration of the first TKI treatment was 30.0 months (median 25.9 months, range 0.9-131). The duration of the first TKI treatment was significantly shorter in patients with sarcopenia than in non-sarcopenic patients (19.1 months vs. 28.78 months, p = 0.012).
Median PFS was 18.1 months and it resulted as significantly longer in non-sarcopenic (24.39 ± 18.96 months) than in sarcopenic (8.46 ± 6.87 months) patients (p = 0.008). Analyzing OS, according to the presence or the absence of pre-treatment sarcopenia, we found better survival in non-sarcopenic patients, approaching the borderline of significance (53.2 ± 41.8 months vs. 37.1 ± 44.3 months, p = 0.07).
At the 12-month follow-up, all sarcopenic patients at baseline (n = 6 patien in remaining sarcopenic. Among 33 non-sarcopenic patients, 9/33 (27.3%) d sarcopenic condition after 12 months of TKI treatment. Overall, at the 12-mo up, 45.4% of patients were sarcopenic. This rate was 33% in the subgroup of D treated with lenvatinib. 45.4% of patients were sarcopenic. This rate was 33% in the subgroup of DTC patients treated with lenvatinib.

Prognostic Factors of Sarcopenia Development during TKI Treatment
Among non-sarcopenic patients at baseline, we evaluated prognostic factors for the development of sarcopenia during TKI treatment (Table 3). Table 3. Clinical-pathological features of 33 non-sarcopenic patients at baseline according to the development of sarcopenia after 12 months of treatment.

All Patients (n = 33) Sarcopenia Group (n = 9)
Non-Sarcopenia Group (n = 24)  SMI value at baseline was significantly lower in patients who developed sarcopenia compared with those without sarcopenia at 12 months follow-up (42.7 cm 2 /m 2 vs. 51.8 cm 2 /m 2 , p = 0.003). Similarly, weight (65.9 kg vs. 81.4 kg, p = 0.04) and BMI (24.5 kg/m 2 vs. 30.1 kg/m 2 , p = 0.02) were lower in patients who developed sarcopenia. Sarcopenia at the 12-month follow-up was more frequent in patients with bone metastases (50% of cases vs. 14% of cases in patients without bone metastases, p = 0.02). The development of sarcopenia at 12 months of treatment did not correlate with age, gender, ECOG Performance Status, histology, type of TKI used as first line, number of sites of distant metastases, the sum of diameters of target lesion, the time from cancer diagnosis and TKI start, duration of treatment with first TKI, the best response with the first TKI therapy and the number of TKI treatment lines.
At multivariate analysis, the only parameter that correlated with sarcopenia development at 12 months follow-up was the SMI value at baseline (OR 0.89, CI 0.78-0.98, p = 0.04).
We also investigated the best SMI cut-off able to predict sarcopenia development by ROC curves analysis. The best SMI cut-off for the female population was 37.6 cm 2 /m 2 . This cut-off had a specificity of 92% and a sensitivity of 100%, with an Area Under the Curve (AUC) of 0.940 95% CI: 0.8358-1 (p < 0.0001) (Figure 3a). In male patients, the SMI cut-off identified was 51.4 cm 2 /m 2 , with a specificity and sensitivity of 80%, with an AUC of 0.88, 95% CI: 0.697-1 (p < 0.0001) (Figure 3b).

Discussion
Sarcopenia is a frequent condition in oncology with a prevalence of 35.3% [26]. This prevalence is higher in palliative settings vs. curative settings and it also results differently in various tumors [26]. Sarcopenia has been extensively reported as a prognostic factor for several human cancers [3,[11][12][13]. Recent studies have shown that a lower SMI value at

Discussion
Sarcopenia is a frequent condition in oncology with a prevalence of 35.3% [26]. This prevalence is higher in palliative settings vs. curative settings and it also results differently in various tumors [26]. Sarcopenia has been extensively reported as a prognostic factor for several human cancers [3,[11][12][13]. Recent studies have shown that a lower SMI value at cancer diagnosis is associated with poor survival in patients with solid tumors [17]. It has also been demonstrated that sarcopenia is associated with a higher incidence of anticancer drug toxicities and with a higher risk of post-surgical complications in oncological patients [16].
Nevertheless, data regarding the prevalence as well as the association between sarcopenia and response to TKI treatment in patients with advanced thyroid cancer, are still lacking. The first set of data was derived from a retrospective study of the Phase III DECISION and ZETA trials. The prevalence of sarcopenia was 49.9%, with a higher prevalence in Asian subjects (73.3%) than in Europeans (32.2) [18]. In two recent Japanese studies, the presence of pre-treatment sarcopenia, measured by SMI, was 61% and 39.1%, respectively [20,21].
In our cohort of 58 Caucasian thyroid cancer patients, sarcopenia was found in about 20% of them before starting TKI treatment. This rate was lower than that observed in other studies on thyroid cancer patients in which the prevalence of sarcopenia ranged from 39% to 61.1% [18,20,21]. A possible explanation of these findings might be the differences in the thyroid cancer population included in the studies. Indeed, in the study of Nishiyama et al. [21], thyroid cancer patients were prior treated with chemotherapy in 13% of cases, the ECOG score 3-4 was present in about 20% of patients and a very high sum of lesions was reported, suggesting more advanced disease. Conversely, in our study, none of the thyroid cancer patients were treated with chemotherapy, the ECOG score ranged from 0 to 2 and all patients were treatment-naive with TKI. In addition, such differences in the prevalence of sarcopenia may also be due to the differences in ethnicities (Caucasian vs. Asian population) between our study and the two published ones [20,21]. Indeed, as previously reported, the rate of sarcopenia was greater in Asian than in European thyroid cancer patients [18].
Several factors contribute to sarcopenia onset in cancer patients. The pathophysiology of cancer sarcopenia is characterized by a negative protein and energy balance, driven by a variable combination of abnormal metabolism and reduced food intake [27]. Tumorassociated inflammation induces alterations in metabolism and cell apoptosis of the skeletal musculature due to pro-inflammatory cytokines [10,28]. Moreover, in these patients, longterm thyroxine suppressive therapy may also contribute [18]. The side effects of TKI such as diarrhea, nausea, vomiting, mucositis, xerostomia, and dysgeusia might further reduce food intake, leading to a condition of sarcopenia [29,30]. Finally, the intrinsic mechanism of TKI itself could contribute to the development of this condition [31].
In our study, sarcopenia correlated with response to TKI therapy. Particularly, the duration of TKI treatment was shorter, with a PFS significantly poorer in sarcopenic compared to non-sarcopenic patients. The role of sarcopenia in advanced thyroid cancer patients was also confirmed with Stepwise Cox regression analysis. Pre-treatment sarcopenia negatively affected PFS in patients with advanced thyroid, suggesting that sarcopenia might be a negative prognostic factor for TKI treatment.
Conversely, although we found better survival in non-sarcopenic patients, approaching the borderline of significance (53.2 ± 41.8 months vs. 37.1 ± 44.3 months, p = 0.07), in Cox regression analysis, pre-treatment sarcopenia was not found to be an independent risk factor for OS, probably due to the small cohort of patients.
Our results are comparable to those reported in an Asian population with advanced thyroid cancer, in which the presence of pre-treatment sarcopenia, measured by SMI, led to a poor outcome [20,21]. Yamazaki and colleagues [20] evaluated 54 patients with DTC and MTC, treated with lenvatinib or vandetanib, demonstrating that sarcopenic patients had a poorer PFS compared to non-sarcopenic patients (p = 0.017). In this study, pre-treatment sarcopenia was the only independent prognostic factor for PFS. Nishiyama and colleagues [21] also found a worse prognosis in sarcopenic than in non-sarcopenic patients.
Only a few studies have investigated the effects of TKI treatment both on anthropometric parameters and body composition [18,19,32]. Huillard and colleagues demonstrated that sorafenib treatment significantly reduced lean body mass (measured at L3). In our study, a significant reduction of SMI values was observed in a subgroup of advanced thyroid cancer patients after 3 months (−4.4%) and 12 months (−10.6%) of TKI therapy. Furthermore, 27% of non-sarcopenic patients at baseline developed a sarcopenic condition after 12 months of TKI treatment. Overall, in our cohort, at the end of a period of about one year of observation, sarcopenia prevalence was around 40% (vs 20.7% at baseline). Similarly, a significant decrease in lean body mass was observed in patients receiving sorafenib, suggesting a significant effect of TKI on muscle mass [18]. Unlike our study, the observation period was only 6 months. It was not well defined if this progressive decrease of lean body mass during TKI treatment may be due to the therapy related-side effects or to a worsening of tumor-associated inflammation.
The only independent prognostic factor of sarcopenia development during TKI treatment was the SMI value at baseline (OR 0.89, CI 0.78-0.98, p = 0.04). Using ROC curve analysis, we identified SMI cut-offs able to predict the evolution towards sarcopenia. Specifically, using a SMI cut-off of 37.6 cm 2 /m 2 for females and 51.4 cm 2 /m 2 for males, we were able to identify patients who developed sarcopenia during TKI treatment with a sensitivity and specificity of more than 80%.
Some limitations related to this study include its retrospective design, the relatively limited sample size, the use of different TKIs, and the partial data regarding drug dosage and adverse events during TKI treatment. Moreover, additional tests able to evaluate the physical performance of patients were not available and the SMI cut-off was calculated using a small cohort of patients without sample size calculation. Nevertheless, this study yielded significant results, since, to our knowledge, this is the first study that has demonstrated that TKI therapy leads to a significant loss of muscle mass, measured by SMI, in thyroid cancer patients. It is also the first study to demonstrate the role of pretreatment sarcopenia as a prognostic factor in a Caucasian population of patients with thyroid carcinoma.

Conclusions
Sarcopenia may be a useful outcome predictor for advanced thyroid cancer patients undergoing TKI treatment. This study highlights the importance of assessing a condition of sarcopenia, both before and during TKI therapy, because prognosis seems to be affected by muscle loss. Further, sarcopenia could potentially be the target of treatment interventions to improve the prognosis in such populations. This evidence further supports the need for a multidisciplinary approach in advanced thyroid cancer [33] that also includes the prevention and treatment of malnutrition and sarcopenia in adult thyroid cancer patients [34].
The prevention of this condition, for example by establishing personalized nutritional support or physical activity programs, ideally before starting anticancer treatment, could be the strategy to obtain a better efficacy of therapy. However, prospective or interventional clinical studies with a larger sample size are needed to validate the correlation between muscle mass loss during TKI therapy and treatment outcomes in patients with advanced thyroid cancer.