November 29, 2021

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What cancer patients is the proton therapy suitable to?

What cancer patients is the proton therapy suitable to?

What cancer patients is the proton therapy suitable to?



What cancer patients is the proton therapy suitable to?

Compared with the high mortality rate, the rate of early detection of liver cancer is very low. More than 90% of it is found to be in the advanced stage. At this time, the opportunity for surgical treatment has been lost, resulting in a 5-year survival rate of only 12%. The 5-year survival rate is as low as 3%.

At present, there are many treatment methods for liver cancer, such as surgery, intervention, and radiotherapy, but the effect is still not very satisfactory. The emergence of proton therapy brings new survival hope for liver cancer patients, especially those with larger liver cancer.

According to many international proton centers, the 5-year local control rate of proton therapy for liver cancer exceeds 80%. Today, let’s look at the advantages of proton therapy for liver cancer and what are the specific beneficiaries?


 

A new choice of radiotherapy for liver cancer-proton therapy

The essence of proton therapy is radiotherapy, but the difference is that it uses proton rays to accurately irradiate the tumor. Its inherent Bragg peak principle makes the radiation release less energy before reaching the tumor. Just like a firework, all the energy is released when the tumor is fired. Achieve better tumor killing effect.

Liver cancer is not very sensitive to radiotherapy, and when the liver tissue is irradiated with a dose that kills liver cancer cells, normal liver cells are also quite killed. The “Rolls Royce” in radiotherapy-proton therapy broke the tolerance of liver cancer radiotherapy, and we turned proton therapy into a high-profile radiotherapy.

Proton therapy is better than ordinary radiotherapy. First of all, the radiation rays are different. Ordinary radiotherapy is X-ray, which belongs to photon rays, with greater side effects, and surrounding healthy tissues are easily damaged; protons use proton rays, which have little radiation damage to the human body.

Secondly, a Bragg peak is formed when proton rays irradiate the tumor. Simply put, all the energy of the rays is released after reaching the tumor site, and the healthy tissues before, after and around the tumor are not affected.

What cancer patients is the proton therapy suitable to?


Comparison of X-ray and proton therapy in the treatment of liver cancer

X-rays release energy when they reach the human skin. Dermatitis is the most common side effect. It consumes more than half of the energy when reaching the tumor, and the effective dose is insufficient. In addition, energy will be emitted behind the tumor, and healthy tissues cannot avoid damage. Proton therapy takes a short time and can be completed within a few minutes. Generally, you can go home after outpatient treatment.

The advantage of proton therapy is that compared with other treatment methods, it can achieve a higher treatment response rate and a tumor control rate of more than 90%, while the liver function is not reduced, and the side effects with the stomach and intestines are not increased. Compared with X-ray therapy, proton therapy has proven to have a higher tumor control rate and overall survival rate, and lower side effects. For example, there are important organs around the liver, such as the lungs, heart, esophagus, spine, etc. X-ray radiotherapy cannot guarantee the extent of damage to these organs, and serious complications may occur and cause death.


For early liver cancer, proton therapy has similar results with surgery or percutaneous ablation

In Japan, where the incidence of liver cancer is also high, the University of Tsukuba began to treat patients with hepatocellular carcinoma with protons in 1985. According to statistics, from 1985 to 1998, a total of 162 hepatocellular carcinoma patients received different hypofractionated proton treatments.

The treatment results showed that the 5-year local control rate (LC) was 86.9%, and there was no significant difference between tumors <5 cm and tumors >5 cm. The 5-year overall survival rate (OS) was 23.5%, and only 50.6% of patients had CP-A cirrhosis, and no grade 3 or higher toxic reactions occurred.

In addition, a new long-term follow-up (median follow-up 55 months) from the University of Tsukuba recently showed that the 5-year local control rate (LC) of patients with 0/A, B, and C stages were 94%, 87%, and 75%, respectively. . The 5-year overall survival rate (OS) was 69%, 66%, and 25%, respectively.

This study also confirmed that the results of proton therapy in patients with stage 0/A are similar to the results of partial hepatectomy or percutaneous ablation.


For larger liver cancers, proton therapy is more suitable

If hepatocellular carcinoma (HCC) patients are more likely to develop radiation liver disease after receiving SBRT (stereotactic radiotherapy), proton therapy may be more suitable.

A study has treated 22 HCC patients with a median tumor size of 11 cm (ranging from 10 to 14 cm), with an irradiation dose of 72.6 GyE/22 f (47.3-89.1 GyE/10~35 f), and a 2-year local control rate (LC) reached 87%, no toxic reactions of grade 3 or higher occurred.


Elderly patients with liver cancer are also suitable for proton therapy

A study by the University of Tsukuba included 21 patients with a median age of 81 years (80 to 85 years). The results showed that the patients had no grade 3 or higher toxic reactions, and the 3-year local control rate (LC) was 100%, 3 years The overall survival rate (OS) was 62%.

This study confirms that elderly patients can also obtain excellent therapeutic effects through proton therapy.


Appropriately increasing the dose of proton therapy can improve the treatment effect and prolong survival

In 2005, researchers in Chiba Prefecture, Japan, reported that after patients received proton therapy with a median dose of 76 GyE/20 f, 80% of 30 patients achieved complete radiological remission, and the 2-year local control rate (LC ) Is 96%.

A retrospective analysis of 242 patients who received 8 proton treatment regimens (52.8~84 GyE/4~38 f) by the Hyogo Prefecture Ion Medicine Center showed that the 5-year local control rate (LC) was 90%, and the 5-year total The survival rate (OS) was 38%.

Researchers at MD Anderson Cancer Center recently reported the results of a retrospective analysis of 46 patients undergoing proton therapy with different segmentation schemes, including radiation doses of 58 GyE/15 f and 67.5 GyE/15 f (56%). They pointed out that for patients with a bioequivalent dose (BED) ≥90 GyE, the median overall survival increased from 15.8 months to 49.9 months, indicating a dose-response effect.

(source:internet, reference only)


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