There are no large-scale statistics on the follow-up of patients with testicular germ cell tumors in China, so we summarize the factors related to follow-up with reference to relevant data from Europe and the United States as follows. The purpose of follow-up: ①Discovery of recurrent lesions: Data show that 50% of patients with recurrent TGCTs can still be cured, mainly depending on the form and stage of recurrence. Patients with late relapse (relapse after 2 years of complete remission) have higher resistance to chemotherapy and poor prognosis. Studies have shown that the recurrence of TGCTs can be better monitored by monitoring serum tumor markers as well as imaging. 8-10 mm density of CT scan is better, otherwise it is prone to false negative results. Serum tumor markers (AFP and/or HCG) are elevated in approximately 2/3 of patients with non-seminomatous recurrence and in approximately 1/3 of patients with seminomatous recurrence. LDH is an important predictor of tumor metastasis, but its use to predict recurrence is controversial. Since some patients with recurrence do not have elevated tumor markers, clinical physical examination and imaging follow-up are also important. ②Detection of second primary tumor lesions: There is a lack of specific monitoring indicators for the monitoring of contralateral testicular primary tumors. Risk factors include: incomplete testicular descent, infertility, testicular atrophy, microscopic testicular stones, and young age of onset. Contralateral testicular biopsy is generally not recommended, but since testicular atrophy is a major risk factor for second primary lesions, contralateral testicular biopsy is recommended when the testicular volume is less than 12 ml (before chemotherapy or 2 years after the end of chemotherapy). ③ Monitor the toxic side effects of chemotherapy or/and radiotherapy: the main long-term risk factors of testicular tumor patients after radiotherapy are cardiovascular disease, secondary tumor and sensory nerve disorder. ④Monitoring of long-term mental health: Since the treatment of testicular tumors may have an impact on sexual function, follow-up can help these patients rebuild their confidence. ⑤ Monitor radiation response. In principle, follow-up includes clinical physical examination, serum tumor markers and imaging examinations, and the third item varies according to the situation of each country. The general principle is that it is effective and economical and has few side effects on human body. Because of the high price of chest CT examination, the radiation is about 400 times higher than that of chest X-ray, and the effect of chest X-ray on lung lesions above 25px is very reliable, so chest X-ray examination is recommended first. Although the accuracy of PET-CT is higher than that of CT (42%), the sensitivity is lower and the cost is higher, so it is not recommended. The duration of follow-up should be consistent with the maximum risk of tumor recurrence and the natural characteristics of the tumor itself. The test should be a good guide to tumor recurrence and have good negative and positive predictive values. Since most tumors recur within 2 years after treatment, they should be closely monitored. recurrence after 2 years has also been reported, so annual follow-up should also be performed for this group of patients. In addition, the effect of treatment is related to the size of the lesion, so detailed examination should also be performed for patients with asymptomatic tumors. The complications after chemoradiotherapy should also be closely observed. (A) Follow-up of stage I seminomatous cell tumor About 75% of seminomatous cell tumors are stage I lesions, 15% to 20% of patients have retroperitoneal lymph node imaging, and 5% have distant metastases. The recurrence rate fluctuates from 1% to 20%, depending mainly on the choice of treatment after radical orchiectomy. Invasion of the testicular omentum, tumors larger than 100px, age less than 30 years, and pathological stage T2 or higher are also risk factors. Statistics show that if there are no risk factors, the risk probability of recurrence is 12%; if there is one factor, the risk probability of recurrence is 15%; if there are two factors, the risk probability of recurrence is 30%. the recurrence rate within 2 years is 15.2%-19.3%, and recurrence after 2 years is less, but recurrence after 6 years has also been reported. The sites of recurrence were, in order, the para-aortic lymph nodes, mediastinum, supraclavicular lymph nodes, and lungs. Only 30% of patients with seminoma have a positive tumor marker response at the time of recurrence. 80% of patients with stage I seminoma will be cured with radical orchiectomy alone, while another 20% will benefit from postoperative adjuvant therapy. Treatment after radical orchiectomy includes surveillance, retroperitoneal radiotherapy, and adjuvant chemotherapy. Both radiotherapy and chemotherapy are sensitive, with survival rates up to 99%, and the cost and side effects of each vary. Only about 30% of patients with seminomatous cell tumors show elevated HCG, so complete reliance on serum tumor markers at follow-up is not reliable. 1.Follow-up after radiotherapy for stage I seminomatous cell tumor Statistics show that the cure rate after surgery with adjuvant radiotherapy can reach 97% to 100%, and the recurrence rate is 0.25% to 1% in 2 to 6 years. Although late recurrence has also been reported, recurrence is most common within 18 months after treatment. The site of recurrence is mainly in the supradiaphragmatic lymph nodes, mediastinum, lung or bone. In a small number of patients, the tumor recurs in the inguinal and external iliac lymph nodes. Side effects of radiotherapy include reduced spermatogenesis, gastrointestinal symptoms (peptic ulcers) and secondary tumors. 50% of patients may experience moderate toxicity. Clinical examination and tumor marker monitoring should be performed every 3 months for 2 years after radiotherapy to the para-aortic lymph nodes, and then every 6 months in the third year, and annually thereafter until the end of 5 years of follow-up. Pelvic CT should be reviewed once a year (or as needed if clinically indicated) and again before the end of the 5th year of follow-up. Chest X-ray should be reviewed twice a year for 3 years, and then once a year until the end of follow-up. 2.Follow-up after chemotherapy for stage I seminoma (Table 6) The recurrence rate of adjuvant chemotherapy after surgery for stage I seminoma is low, and a group of long-term follow-up reports showed that the recurrence rate was about 3%. Another group with a 5-year follow-up reported a recurrence rate of 6.1%, with 80% of recurrences occurring in the abdomen, whereas patients treated with paraaortic lymph node radiation rarely had abdominal recurrences. Given that there is still a risk of late onset slow-growing retroperitoneal teratoma after adjuvant chemotherapy, CT of the abdomen is still required. Therefore, it is recommended that chest radiographs be reviewed twice a year for 3 years after chemotherapy and again before the end of the 5-year follow-up. CT abdomen is examined twice in the first year and once a year thereafter. If there is a history of scrotal invasion or pelvic surgery, CT pelvic examination is required. Clinical examination and tumor marker examination should be done 1 month after chemotherapy, every 3 months for 2 years, every 6 months in the third year, and every year thereafter until the end of 5-year follow-up. It is also believed that the follow-up should last up to 10 years. (B) Follow-up after stage I nonseminomatous cell tumor (Table 7) Numerous studies have shown that the recurrence rate of patients with clinical stage I NSGCT after radical orchiectomy is 30%, of which approximately 80% recur within 12 months of follow-up, 12% recur in the second year, 6% in the third year, and the recurrence rate decreases to 1% in the fourth and fifth years, with occasional recurrences after a longer period of time reported. Serum tumor markers were normal in 35% of patients at the time of recurrence, and the recurrent lesions were located in the retroperitoneum in about 20% of patients and in the mediastinum and lung in about 10%. The choice of therapeutic measures: (i) close monitoring, (ii) retroperitoneal lymphatic dissection with preservation of nerves, and (iii) adjuvant chemotherapy. The follow-up schedule varies depending on the choice of therapeutic measures. (1) Follow-up of patients with postoperative monitoring: long-term follow-up (at least 5 years) is possible if the patient is willing and complies with monitoring. With closely monitored measures, recurrence is possible in 30% of patients, with recurrence occurring mostly within 2 years, and chest recurrence foci with positive chest radiograph changes have been reported in 19% of patients. Therefore, CT scan of the chest should be examined only when necessary, and chest film review is recommended. Close monitoring is recommended for 2 years after surgery, especially in the first year. Clinical physical examination, tumor markers and chest radiographs are performed every 3 months during the first year. One study showed no statistically significant difference between 2 CT exams and 5 CT exams a year. Therefore, CT examination of the abdominal pelvis every 6 months in the first year is recommended. (2) Follow-up of patients with postoperative chemotherapy: Studies have shown that adjuvant chemotherapy is more effective, with a recurrence rate of about 3% to 4%, most of which occur within 2 years, and there are reports of retroperitoneal teratomas, so abdominal CT examinations are recommended within 2 years after chemotherapy and after 2 years when necessary. (3) Follow-up of patients after retroperitoneal lymph node dissection (Table 8): Fewer patients had retroperitoneal recurrence after RPLND, and if recurrence occurred, it usually occurred in the chest, neck and surgical incision margins. In cases without lymphatic metastases, the recurrence rate was 10% to 13%, mostly occurring in the first year; therefore, chest radiographs need to be reviewed every 3 months in the first year after surgery. In addition, the low rate of retroperitoneal recurrence after RPLND presupposes precise and complete retroperitoneal lymph node dissection, and abdominopelvic CT is recommended within 2 postoperative years. (III) Follow-up of stage IIa/IIb progressive (metastatic) germ cell tumors The extent of progressive (metastatic) germ cell tumor lesions and response to treatment correlate with survival rates. Typically, higher N stage is associated with greater recurrence, and the volume of the primary tumor also influences the outcome of NSGCT patients treated. In stage II NSGCT patients, regardless of the treatment, a 97% survival rate can still be achieved if recurrence is detected early. Chemoradiotherapy achieves better outcomes in most patients. Cisplatin-based combination chemotherapy and surgery can achieve a cure rate of 65% to 85%, depending on the extent of the initial lesion. Patients with complete sensitivity to chemotherapy are approximately 50% to 60%, and an additional 20% to 30% of patients can still achieve a disease-free state with chemotherapy followed by surgery. The main reasons for treatment failure in patients with progressive NSGCT are the complete insensitivity of large lesions to chemotherapy or failure to remove residual teratomas after chemotherapy, and the development of chemoresistance in about 8.2% of patients. Follow-up strategy after chemoradiotherapy for stage IIa/IIb progressive germ cell tumors: clinical examination, tumor markers and chest radiographs are recommended to be reviewed every 3 months for 3 years after treatment, then every 6 months until 5 years, and annually thereafter. CT scan of abdomen and pelvis is still recommended to be examined twice a year. (IV) Follow-up of stage IIc-III progressive (metastatic) germ cell tumor Patients often have residual tumor after chemoradiotherapy, which is difficult to remove by surgery, and if the mass is larger than 75px, PET-CT has higher diagnostic value. CT examination is recommended every six months.