Chordoma is a rare type of bone tumor with an incidence rate of 0.08/100000.

Approximately 10% of adult bone malignancies and 1-4% of pediatric bone malignancies.

Chordoma mainly occurs in the central axis bone, such as the skull base slope and sacrococcygeal bone, and very few can occur outside the central axis bone, such as rare areas such as the lungs, mediastinum, flexor synovial sheath of the little finger, and gingiva.

Its growth is relatively slow, but it has strong local invasiveness, often leading to local pain in the affected area.

Due to chordoma often adjacent to important nerve tissues such as the brainstem and spinal cord, its growth often compresses surrounding nerve tissues, leading to complications such as limb sensory and motor disorders and paralysis, seriously affecting the quality of life of patients, and even threatening their lives.

Surgery is the main treatment for chordoma, but due to the unique and complex anatomical structure of the spine, tumor resection often fails to obtain negative anatomical boundaries, resulting in a high postoperative recurrence rate and poor long-term efficacy of chordoma.

Therefore, in order to better improve the treatment effect of chordoma, advanced radiotherapy techniques such as proton therapy have been increasingly applied in the treatment of chordoma in recent years.

Compared with traditional radiotherapy, proton therapy can increase the radiation dose at the target site, reduce damage to surrounding tissues, and thus improve treatment effectiveness.

Proton therapy can increase the radiation dose of tumors while minimizing the risk of organ damage [1], which has great advantages in the treatment of chordomas.

Approximately 32% to 42% of chordomas are located at the base of the skull, most of which are low-grade malignancies and grow slowly.

However, it is mainly characterized by invasive local growth, often accompanied by osteolytic destruction. The tumor is often large and easily affects the surrounding cranial nerves, causing the great arteries to shift or wrap around and invade the cavernous sinus.

Therefore, surgery is difficult to completely remove, and postoperative recurrence is highly likely.

Therefore, the current treatment option for skull base chordoma is surgical resection followed by radiation therapy.

Due to the controversy surrounding conventional radiotherapy, although it can prolong survival, most patients sacrifice some neurological function at the cost.

Therefore, proton therapy, which has dosimetric advantages and is beneficial for protecting normal tissues, has become the mainstay of chordoma treatment.

The Radiation Oncology Department in the United States published a study in 2021 evaluating proton therapy for skull base chordoma.

Researchers believe that proton therapy used for postoperative radiotherapy of chordoma can maximize the protection of organs at risk, such as the brainstem and visual organs.

The study included 10 patients with skull base chordoma who received proton therapy from 2017 to 2020.

The results showed that the local control rate and overall survival rate were as high as 100% [3].

And there were no complications of level 3 or above in this study.

Overall, proton therapy not only has good results for chordomas in the skull base region, but also protects important surrounding organs.

So, how effective is proton therapy for people of different ages?

In 2019, a study on proton therapy for chordoma was published in the Journal of Surgical oncology.

The study included 20 adult patients with non metastatic chordoma and chondrosarcoma who underwent proton therapy from 2010 to 2014.

The median follow-up time was 37 months.

The results showed that the 3-year local control rate was 86%, and the 3-year progression free survival rate was 81% [5].

Proton therapy has always been considered to have great advantages in the treatment of pediatric tumors, so what is the effect of proton therapy on pediatric chordoma?

The Department of Radiation Oncology at the University of Florida School of Medicine published a study on proton therapy for pediatric chordoma in 2021.

Researchers believe that due to the location and high dose required for disease control, theoretically, pediatric chordoma is highly suitable for proton therapy [4].

The study included 29 children with non metastatic chordoma who received proton therapy with a median age of 14.8 years between 2008 and 2018.

The median follow-up time was 4.3 years, and the predicted 5-year local control rate was 85%. The 5-year progression free survival rate was 82%, and the overall 5-year survival rate was 86%.

The actual results are better than the predicted results.

The actual results showed that the 5-year local control rate was 92%, the 5-year progression free survival rate was 92%, and the overall 5-year survival rate was as high as 91% [4].

Overall, proton therapy for chordoma has good results in both adults and children, but its effect is more significant in children.

And for chordomas adjacent to important tissues and organs such as the skull base, proton therapy is more conducive to protecting surrounding normal tissues.