Patient: Description (time of onset, main symptoms, hospital visited, etc.): The onset of the swelling on the left thigh was about six months, and there was a swelling as big as a fist. I just had surgery at Friendship Hospital, and the pathology result is extra-osseous mucinous cartilage low-grade malignant tumor. I want to know how to treat it next, and whether to use radiotherapy. Is there any better treatment method? Doctor: The possibility of metastasis of low-grade malignant chondrosarcoma is low. Surgery is the main treatment, and the recurrence rate is also relatively low if complete resection is done, and radiotherapy is generally not needed (nor is it sensitive). As to whether you need radiotherapy, it depends on whether the surgical resection is complete, and if the cut edge is positive, radiotherapy is considered. Patient: Thank you for your advice, the surgical resection was good, the resected tumor is a very whole one, what are the chances of metastasis, the hospital asked us to be hospitalized for radiotherapy, I am still hesitant now, I don’t know what to give him next Doctor: I think you should follow the advice of the surgeon, they may think there is a risk of recurrence before suggesting you radiotherapy. Because of the low malignancy, the risk of distant metastasis is low and it is important that it does not recur. Patient: Because the surgical resection is a tumor with intact envelope, the orthopedic surgeon said that the surgery is cleanly cut and suggested us to see oncology, who told us to do radiotherapy, I don’t know how to do radiotherapy, please give your guidance. Doctor: The surgical resection of malignant tumor requires not only the “intact envelope” but also the normal tissues around the tumor in the range of 3-5cm, which is the surgical principle of extended resection. Therefore, I don’t know if your surgical resection is enough. For the safety period, it is certainly beneficial to do radiotherapy to reduce the risk of recurrence. However, because chondrosarcoma is not very sensitive to radiotherapy, the dose of radiotherapy is demanding and may be more damaging to the body and cannot completely avoid recurrence. Another option is to continue observation, pay attention to timely review, and expand resection again early if a recurrence is found.