Systematic review
The systematic review included 148 articles (mostly case and case series reports), with a total of 381 cases of LCS (Figure 7). In 2 of them (0.5%) the authors described the coexistence of LCS associated to a PTC. None of them had cervical metastasis. In terms of quality, the articles were classified within medium quality values.
The sample consisted of 254 men (74.3%) and 88 women (25.7%) with a mean age of 61.1 ± 12.1. Diverse symptoms were described in 325 patients (85.3%). A different grade of dyspnea was the most commonly reported symptom (42.8%) followed by hoarseness (35.7%) and neck mass sensation (10.8%). Most of the patients reported more than one symptom. Impairment of at least one vocal cord mobility was reported in 66 patients (17.3%). Imaging studies were described in 213 patients (55,9%). CT scan was the most commonly used, in 209 patients, followed by MRI in 46. Other techniques as ultrasound or X-ray were also described. In Figure 8, more information regarding demographics, symptomatology, location, and imaging is provided.
Tumoral location was reported in 340 patients (89.2%). The cricoid cartilage was the most commonly affected with 271 cases (79.9%), followed by the thyroid cartilage in 67 cases (19.7%). In 41 patients (10.8%) the tumor involved more than one anatomical site. Different treatment modalities were used. Total laryngectomy was reported in 131 patients (34.4%), local excision in 104 cases (27.3%), partial laryngectomy in 92 (24.1%), and laser surgery in 34 patients (8.9%). Uni or bilateral neck dissection was reported in 18 cases (4.7%). First choice radiotherapy was used in 7 patients (1.8%). Adjuvant therapy with RT was described in 28 patients (7.34%) and chemotherapy in 2 patients (0.52%). The size of the tumor was reported in 135 patients (35.4%), being the mean size 3.8 ± 1.7 cm. Histological information was found in 323 patients (84.7%). Pathological grading was reported as Grade I (well-differentiated) in 210 cases (67.1%), Grade II (moderately-differentiated) in 62 cases (19.8%), Grade III (poorly differentiated) in 8 cases (2.6%) and Grade IV (dedifferentiated) in 18 cases (5.8%). Other cases were reported as clear cell CS, or myxoid CS. Distant metastases were unfrequent, and appeared in 21 patients (5.5%) in different locations like lungs, soft tissue, bone or peritoneum. Lung metastasis was the most frequent location, being present in 15 cases (71.4 %). The mean follow-up time was 57.7 ± 53.4 months. In this period, tumoral recurrence was reported in 62 cases (16.3%). Total Laryngectomy was the treatment of choice in 25 of the recurrences (6,6%). Local excision and laser were used in 18 patients (4.7%) while partial laryngectomy was described in 8 patients (2.1%). Death was reported in 47 patients (12.3%), mostly as “not related or other cause” (74%), or “distant metastasis” (17,4%). Only 8.7% were reported as “dead of disease” . Death was found to be more frequent in those patients with tumoral recurrence who were treated with total laryngectomy (55.3%, p = 0.001). In Figure 9 additional information about treatment, tumoral characteristics, and follow-up period is provided.
Using Kaplan-Meier curves, a mean survival of 207.5 months (95% CI 176.4-238.7 months) is estimated (Figure 10). Regarding survival in relation with tumoral location, the estimate is lower for those cases with combined location, with 98.5 months (95% CI 73-124 months) compared to those affecting only one location, with a mean of 191.6 months (95% CI 163.1-220 months) (log-rank = 6.6, p = 0.01) (Figure 11). Survival is also affected by histological differentiation, being the lowest for grade IV (dedifferentiated) with 118.7 months (95% CI 64.8-172.6 months) and the longest for grade I (well-differentiated) with 253.8 months (95% CI 215-292.5 months) (log-rank = 18.3; p = 0.003) (Figure 12).
Taking into account treatment modality, the estimate for survival is lower for those who underwent total laryngectomy with 156.6 months (95% CI 127.5-185.6 months) compared with those who were treated with laser excision with 276.1 months (95% CI 229.4-322.9) (log-rank = 11.7; p=0.008) (Figure 13).