Abstract】 Objective To investigate the clinical characteristics, treatment and prognosis of adenoidal soft part sarcoma (ASPS). Methods The clinical data of 58 cases of ASPS admitted to our hospital in the past 40 years were retrospectively analyzed and studied, and the survival analysis was performed with the follow-up data. Results There were 27 male cases and 31 female cases. The age of diagnosis ranged from 8 to 56 years, with an average of 25.1 years. The tumors occurred in 33 cases in the lower extremities, 13 cases in the upper extremities, 6 cases in the head and neck, 4 cases in the trunk, 1 case in the psoas major muscle, and 1 case in the vagina. Except for 6 cases in which distant metastases were found at the time of consultation and were not treated surgically, the other 52 cases were treated surgically. Among them, 19 cases underwent local excision and 33 cases underwent extended excision. 19 cases received adjuvant radiotherapy or chemotherapy after surgery. The overall survival rates for the whole group were 89.54%, 74.10% and 57.68% for three, five and ten years. The median survival time was 125 months. The three-, five-, and 10-year survival rates were 79.55%, 67.15%, and 49.74% for male patients and 100.00%, 81.57%, and 65.25% for female patients (P=0.026). Conclusion Adenoid soft tissue sarcoma is not highly malignant, with relatively slow tumor growth and a low local recurrence rate, but distant metastasis is more common. The lung is its most common metastatic organ. However, even if lung metastasis occurs, the prognosis is still good. Surgical resection is still the only effective treatment for limited stage adenoid soft tissue sarcoma. Adjuvant postoperative radiotherapy is not satisfactory for controlling local recurrence and distant metastases. Whether the prognosis of female patients is better than that of males is related to the translocation of the X chromosome, which needs to be further investigated. Alveolar soft part sarcoma (ASPS) is a rare soft tissue tumor, named after its unique microscopic glandular vesicle-like structure, and the origin and biological behavior of ASPS are still unclear, so its clinical characteristics, treatment options and prognosis need to be further investigated. In the past 40 years, 58 cases of ASPS were admitted to our hospital and are analyzed and reported as follows. Data and methods 1. General data: A total of 58 cases of adenoid soft tissue sarcoma were admitted to the Cancer Hospital of Chinese Academy of Medical Sciences between July 1967 and June 2006. There were 27 male cases and 31 female cases. The age at diagnosis ranged from 8 to 56 years, with a mean of 25.1 years. Among them, 45 cases were ≤30 years old and 13 cases were >30 years old. Tumor sites: 33 cases in lower limbs: 2 cases in buttocks, 22 cases in thighs, 8 cases in calves and 1 case in feet; 13 cases in upper limbs: 3 cases in shoulders, 4 cases in upper arms, 5 cases in forearms and 1 case in hands; 4 cases in trunk: 3 cases in back and 1 case in chest wall; 6 cases in head and neck: 2 cases in tongue, 1 case in eyes, 1 case in face, 1 case in jaw and 1 case in neck; other sites: 1 case in psoas major muscle and 1 case in vagina. All tumors were solitary. Symptoms and signs: The main symptom was a slow-growing deep soft tissue mass. Most were painless, and a few could have soreness or numbness. The duration of preoperative disease ranged from a few days to several years, with the longest being 10 years and the average being 16.7 months. 2. Surgical treatment: Except for 6 cases in which distant metastases were found at the time of consultation and were not treated surgically, the remaining 52 cases were treated surgically, of which 31 cases were operated in our hospital and 21 cases were operated outside. The tumor was locally resected in 19 cases (2 cases were only palliatively resected due to distant metastasis or huge and extensive tumor invasion) and 33 cases were expanded. Adjuvant treatment: Among the 50 patients with complete resection, 19 cases received postoperative adjuvant treatment. 15 cases received local radiotherapy (dose 40Gy-70Gy), among which 3 cases also received prophylactic total lung irradiation (15Gy); 4 cases received combined chemotherapy (vincristine, cyclophosphamide, epi-amycin, pedialyte glycosides, etc.) for 3-8 cycles. 4. Pathological examination: Gross observation: the tumors were all located in the deep muscle or muscle membrane, oval or round, and partly nodular in shape. The size of tumors ranged from 1 cm to more than 20 cm. Among them, >5 cm:24 cases; 2-5 cm: 29 cases; ≤2 cm:5 cases. Most of the tumors were well-defined, and some of them had pseudo-envelope or incomplete envelope. The cut surface was gray-brown or gray-white, which could be accompanied by hemorrhagic necrosis, and a few had cystic changes. Microscopically, the tumor cells were large, polygonal or round, with clear boundaries; the nuclei were round or oval, located in the middle of the cells or in a deviated position; the nucleoli were obvious, and the cytoplasm was abundant and lightly stained. The tumor cells were nested and surrounded by abundant sinusoidal or lacunar blood vessels, which could have a typical “glandular vesicle-like” structure. 5. Follow-up and statistical analysis: The follow-up was conducted by outpatient review, letter or telephone, and the deadline for follow-up was July 31, 2006. All 58 cases in the group were followed up, with a follow-up rate of 100%. The follow-up period ranged from 2 to 246 months, with a median of 52 months. Survival analysis was performed using SPSS13.0 statistical software, applying Kaplan Meier method, and parallel Log rank significance test. Results 1. Recurrence and distant metastasis: Among the 50 patients with complete tumor resection, 11 cases showed local recurrence, with a recurrence rate of 22%. In the whole group of 58 cases, 31 cases (53%) had lung metastasis, among which 9 cases occurred at the time of consultation or within 6 months after surgery; 7 cases had lung metastasis more than 5 years after surgery, and the latest case of lung metastasis occurred 106 months after surgery. The median time to lung metastasis was 27 months after surgery or after diagnosis. The survival rates of one, three and five years after lung metastasis were still up to 96.77%, 57.88% and 49.61%, with a median survival time of 53 months. 14 cases combined with distant metastasis from other sites (bone, brain, liver, lymph nodes, abdomen, rectum, breast, etc.). 2. Prognosis: The overall survival rates of the whole group were 89.54%, 74.10% and 57.68% for three, five and ten years. The median survival time was 125 months. The three-, five-, and 10-year survival rates were 79.55%, 67.15%, and 49.74% for male patients and 100.00%, 81.57%, and 65.25% for female patients (P=0.026). The three-, five-, and 10-year survival rates for the 50 patients with complete tumor resection were 97.44%, 79.83%, and 61.08%. Discussion Adenoid soft tissue sarcoma is a rare soft tissue tumor. The incidence of this tumor has been reported in the literature to be only 0.5% to 1.0% of soft tissue sarcomas [1]. Regarding the tissue origin of ASPS, it is still unclear and several hypotheses have emerged: granulocytic myoblast origin; non-chromophobic paraganglial origin; glomerular paraglomerular cell origin; and muscle tissue origin, but none of the hypotheses can be reasonably and comprehensively verified, so ASPS is still classified as a soft tissue tumor of unknown origin. However, in recent years, an increasing number of studies have suggested that ASPS may originate from muscle tissue, especially transverse muscle tissue: (1) ultrastructural observations revealed that fine granular and rod-like crystals with diagnostic significance were visible in the ASPS cytoplasm, which were structurally similar to actin [2]. (2) Immunohistochemical studies showed that muscle-related markers such as actin, junctional protein, and wave protein were expressed in ASPS to varying degrees [1]. (3) Molecular biology studies suggest that mRNAs such as myoregulatory proteins and α-actin can be expressed in ASPS [3]. ASPS predominates in young people, with a peak age of onset of 15-35 years. There are slightly more females than males. The tumors are found in the deep soft tissues of the extremities, especially in the lower extremities. In this group, 46 cases occurred in the extremities, accounting for 82.4%, including 33 cases in the lower extremities, accounting for 56.1%. The clinical symptoms were mainly slow-growing deep soft tissue masses, and the disease duration was often long. The average duration of disease in this group of cases was 16.7 months and the longest was 10 years. Imaging examination was not specific except for suggesting a tumor with high blood supply [4]. Unlike other soft tissue sarcomas, the local recurrence rate of ASPS is not high. It is reported in the literature to be about 20-30%. However, Kayton et al [5] and Ogose et al [6] analyzed that the recurrence of ASPS is associated with the local residual of the tumor. and reported that the recurrence rate of ASPS was 0% in all the case groups in which they performed extended resection. In our group, 11 cases showed local recurrence, and all of them underwent only local resection at the first surgery, which is consistent with the results of Kayton and Ogose. ASPS is extremely rich in blood supply, and pathological examination often reveals gross tumor vessels, making it highly susceptible to hematogenous metastasis [1]. The lung is the most common site of its metastasis, but there is no obvious pattern in the time of occurrence of pulmonary metastasis. In our group, 31 cases (53%) had pulmonary metastasis, among which 9 cases occurred at the time of consultation or within 6 months after surgery; 7 cases had pulmonary metastasis more than 5 years after surgery, and the latest case of pulmonary metastasis occurred at 106 months after surgery. However, ASPS has a slow growth rate and insidious disease progression, and even if lung metastasis occurs, the prognosis is still relatively good. The survival rates of one, three and five years after pulmonary metastasis in this group were still 96.77%, 57.88% and 49.61%, and the median survival time was 53 months, which was significantly better than other soft tissue sarcomas. However, the prognosis is not good if brain metastasis occurs. In our group, all 5 cases died within 6 months after brain metastasis occurred. Surgical resection is still the only effective treatment for limited stage adenoid soft tissue sarcoma [1]. As with other soft tissue sarcomas, complete resection of the tumor is essential to control local recurrence, distant metastases, and to reduce the morbidity and mortality rate. In our group, 33 cases of extended resection were performed without local recurrence and only one case died in the 52nd month after surgery, with survival rates of 100.00%, 90.91%, and 90.91% for three, five, and ten years; 19 cases of local resection were performed, of which 11 cases (57.9%) had local recurrence and 8 cases had died, with survival rates of 90.48%, 68.43%, and 43.54% for three, five, and ten years. Sherman et al [7] have suggested that adenoid soft tissue sarcoma should be routinely treated with adjuvant radiotherapy to reduce the rate of local recurrence. However, for patients who have undergone extended resection, local recurrence is rare or even 0%, so local recurrence is not an important factor in prognosis [6], so we do not advocate routine adjuvant radiotherapy after surgery. For postoperative adjuvant chemotherapy, neither the literature reports nor we found its necessity [6]. Therefore, for limited-stage adenoid soft tissue sarcoma: we recommend an extended resection or radical resection with the aim of complete removal of the tumor; if the first surgical margin is not clean or suspicious, we still recommend aggressive reoperation to expand the surgical scope and avoid tumor remnants; we only recommend adjuvant postoperative radiotherapy if the tumor is in a special location and there is no sufficient scope for extended resection. Gender may be an important factor in the prognosis of adenoid soft tissue sarcoma. The survival rates of our male patients were 79.55%, 67.15%, and 49.74% at three, five, and ten years, while the survival rates of female patients were 100.00%, 81.57%, and 65.25% at three, five, and ten years (P=0.026). In recent years, molecular biology studies have revealed that there is a specific der(17)t(X:17)(p11.2:q25) disequilibrium translocation in ASPS. This translocation necessarily implies the acquisition and deletion of chromosomal break region Xp and 17q25 region.Bu et al [8] found that many clinical features of adenoid soft tissue sarcoma are associated with X chromosome translocation. Whether the better prognosis of female ASPS patients compared to males is related to the translocation of the X chromosome (acquisition of the Xp chromosome break region) is to be further investigated.