Inform, Empower, Connect

In this blog we look at a study by Kuo et al, where the results will be used for a larger ongoing Children’s Oncology Group Trial. The larger trial is looking at surgical outcomes for patients with osteosarcoma (OS) which has spread to the lungs (NCT05235165/ AOST2031).

OS is a rare type of cancer, and it is part of a group of cancers which are known as sarcomas. OS is a primary bone cancer. Roughly 20% of patients who have OS also have bone cancer that has spread beyond the first area of growth and into the lungs. This is known as pulmonary metastasised cancer and in this blog, we refer to it as PM-OS. (Huang et al, 2019). The lungs are the most common place for the spread of OS. The lungs are also the most common place for the cancer to reappear after treatment (this is known as relapsed osteosarcoma). 92% of patients with OS included in the European and American Osteosarcoma Study had relapses involving the lungs (Smeland et al, 2019).

What treatments are available?

The treatment for PM-OS involves surgical intervention combined with chemotherapy. The chemotherapy treatment can take place before or after surgery. They are:

  1. Thoracotomy: This is where a surgical cut is made into the ribs to access the lungs. The cancerous growth is then removed.
  2. Thoracoscopy: This is a less invasive form of treatment than a thoracotomy. This is for the removal of cancerous growth.
  3. CTT: This treatment combines both thoracoscopy and thoracotomy. In this study, this was defined as patients which had a thoracoscopy as the first line of treatment, with a change to thoracotomy in the same episode of surgery.

Outcomes for PM-OS are generally poor. Therefore, by looking at the current surgical procedures for this group of patients, we can understand if any treatment has preferable outcomes. This study was a retrospective study. This type of a study looks at data from one treatment clinic. It provides insight into future trials which could improve outcomes for this group of patients.

How did the researchers do this?

61 patients with PM-OS were identified through the medical records at Children’s Hospital Los Angeles in USA. The records were searched from 2004 to 2018. The average age at diagnosis was 13 years old. Patients had primary PM-OS or presented with it at their first relapse.

The clinical data that was used for analysis included the:

  • Tumour response to chemotherapy (this is known as a histological response)
  • Surgical intervention (thoracotomy, thoracoscopy and CTT)
  • Post-surgery outcomes including infection, pain medication, and lung collapse (this is known as pneumothorax).

Outcomes were event-free survival (length of time, no treatment, or recurrence of the OS) and overall survival (length of time until death from any cause).

What did the results show?

  1. There were notably more post-operation events in the patients that had a thoracotomy. This included the use of pain relief, lung collapse, and infection. This is understandable due to the invasive nature of the procedure.
  2. In most patients with OS who had it in one area at initial diagnosis, their most common site of relapse was in the lungs.
  3. This suggests that there could have been ‘chemotherapy resistant micro metastases’ during the first diagnosis. Micro metastases are when there are microscopic cancerous cells which have escaped the first tumour site, but it cannot be found using the usual diagnosis methods such as scans.
  4. Patients who did not responded to chemotherapy, but they had surgery showed improved overall survival length. This suggests that surgical intervention is essential for better management of outcomes in PM-OS patients.  Pain was higher for those who had thoracotomy more than once. This may be due to the repeated incisions and the previous scarring causing increased neuropathic (nerve) pain.
  5. Lung collapse rates were lower in those who had thoracoscopy procedures more than once, compared to other procedures. This could be due to the less invasive nature of the procedure.

What does this mean?

There were some limitations to this study. This includes the small sample size. The researchers analysed the data after the operations had been done. This meant that they could not control what happened during each surgery. The term for this is ‘limited risk control’. However, the data from this study will be used in a wider prospective clinical trial. This trial aims to learn outcomes in these procedures that are done in PM-OS patients. This small-scale study tells us why surgical treatment is important for such patients. The study also highlights the need for appropriate post-operative management to improve outcomes for them.

The details for the larger ongoing clinical trial can be found here. Clinical trial number NCT05235165/AOST2031


  1. Kuo C, Malvar J, Chi YY, Kim ES, Shah R, Navid F, Stein JE, Mascarenhas L. Survival outcomes and surgical morbidity based on surgical approach to pulmonary metastasectomy in pediatric, adolescent and young adult patients with osteosarcoma. Cancer Med. 2023 Oct;12(20):20231-20241. doi: 10.1002/cam4.6491. Epub 2023 Oct 6. PMID: 37800658; PMCID: PMC10652329.  
  2. Smeland S, Bielack SS, Whelan J, et al. Survival and prognosis with osteosarcoma: outcomes in more than 2000 patients in the EURAMOS-1 (European and American osteosarcoma study) cohort. Eur J Cancer. 2019;109:36-50.
  3. Huang X, Zhao J, Bai J, et al. Risk and clinicopathological features of osteosarcoma metastasis to the lung: a population based study. J Bone Oncol. 2019;16:10023