gamma knife, wave knife , Thom knife, X knife... all the way to the highest proton knife, essentially radiation therapy (radiotherapy) , that is, use radiation to kill cancer cells.
If classified from the professional perspective of a radiotherapy doctor, the first thing to do is to see what the released rays are: electrons, photons, protons, or heavy ions. What's the difference between these things? Everyone needs to review the common sense of high school physics: electrons carry a negative charge and have a small mass (but not 0); photons have no mass and are not charged; protons carry a positive charge and have a mass of 1836 times that of electrons; heavy ions carry a positive charge and have an integer multiple of protons (for example, the mass of carbon ions is about 12 times that of protons) ...
But, knowing what does these things have to do with anti-cancer treatment? Isn't it taking the college entrance examination? !
The relationship is as follows:
- The most common ordinary radiotherapy , generally release photons, that is, use high-energy photon lines to kill cancer cells. A complete course of treatment usually costs about 50,000 yuan, included in the national medical insurance ;
- gamma knife, thom knife, and wave knife also release photons, but the machines used are different, the single energy is greater, and the positioning is also the photons. More accurate, the charge is around 1.1 million yuan for html, which may not necessarily be reimbursed by medical insurance;
proton radiotherapy , which releases protons, and heavy ion radiotherapy , which releases heavy ions. After a proton with a certain mass and positive charge obtains high energy and high speed, the so-called Bragg peak will be formed, allowing anti-cancer energy to be released accurately inside the tumor tissue, with little impact on the surrounding normal tissue. However, for such high-end radiotherapy, charges about 300,000 yuan, which is fully self-paid.
went around a long way, and the biggest and most practical problem in the minds of patients was still not solved: how big is the difference between the efficacy and side effects of html's 1.3 million yuan of proton heavy ion radiotherapy and 40,000 or 50,000 yuan of routine radiotherapy? is a world of difference or is it as small as a hair?
First tell you the answer: In most cases, proton heavy ion radiotherapy has similar efficacy to conventional radiotherapy, and the side effects are reduced to a certain extent. The conclusion of
is not the author's personal experience or a silence, but is supported by multiple authoritative data.
For example, as early as 2016, the top academic journal of the international radiotherapy community, the official journal of the European Society of Tumor Radiation Therapy ("Green Skin") reported the results of a group of case-control research, using proton heavy ion radiotherapy and routine intensity-modulated radiotherapy to treat head and neck squamous cell carcinoma respectively. The former is 50 cases, and the latter is 100 cases that match age, gender, race, and disease severity.
results show that the patients with had no disease progression and overall survival in the two radiotherapy modes. However, due to adverse reactions such as oral mucosal inflammation, dysphagia, and lumen stenosis caused by radiotherapy, nasogastric feeding tubes were required to place a nasal feeding tube for nutritional support, or the proportion of decreased significantly due to the inability to keep up with nutritional support, and the proportion of decreased significantly in (from 24.7% to 8.0%) ; while other adverse reactions, such as oral mucositis, dry mouth , weight loss, and fatigue, there was no statistical difference between the two groups.
Of course, some people will say that the above study only included 150 patients, and there is only one type of squamous cell carcinoma of the head and neck, which is not widely convincing.
In 2020, Professor James M Metz's team of High School of Pennsylvania provided another comparative study with 1,483 cases covering almost all common tumors. 1092 patients received routine IMO radiotherapy and 391 patients received proton heavy ion radiotherapy.
Results show that there was no median disease progression generation period and overall survival in the two groups of ; the incidence of severe adverse reactions in was significantly reduced within 90 days in the proton heavy ion radiotherapy group (the incidence of serious side effects of grade 3 and above was cut from 27.6% to 11.5%; the incidence of adverse reactions of grade 2 and above was reduced from 84.8% to 74.2%) .
To sum up, in most common cancers and common situations, the efficacy of proton heavy ion radiotherapy and routine radiotherapy is almost the same, but the former can reduce the incidence of adverse reactions to a certain extent. As for whether it is cost-effective to reduce the incidence of adverse reactions, patients have different opinions.
However, in some special cancers (such as adenoid cystic carcinoma ) and special parts (such as close to the brain stem, involvement of the spinal cord, etc.) has unique advantages in radiotherapy.
Recently, JCO magazine released a prospective randomized controlled clinical trial. In patients with meningeal metastasis in solid tumors, the efficacy of proton heavy ion radiotherapy and routine intensity-modulated radiotherapy was compared. There were 42 and 21 patients in the two groups respectively.
Results show that the brain has no disease progression and generation time in the proton heavy ion radiotherapy group is significantly longer (2.3 months vs. 7.5 months) , and the median overall survival time is also longer (6.0 months vs. 9.9 months) , but there is no statistical difference in the incidence of grade 3-4 adverse reactions in the two groups - the brain and spinal cord, after all, it is the most precious organ in the human body. This special part, proton heavy ions, is still beneficial if it spends 300,000 yuan.
References:
[1]. Intensity-modulated proton beam therapy (IMPT) versus intensity-modulated photon therapy (IMRT) for patients with oropharynx cancer - A case matched analysis. Radiother Oncol. 2016 Jul;120(1):48-55
[2]. Comparative Effectiveness of Proton vs Photon Therapy as Part of Concurrent Chemoradiotherapy for Locally Advanced Cancer. JAMA Oncol. 2020 Feb 1;6(2):237-246
[3]. Randomized Phase II Trial of Proton Craniospinal Irradiation Versus Photon Involved-Field Radiotherapy for Patients With Solid Tumor Leptomeningeal Metastasis. J Clin Oncol. 2022 Jul 8;JCO2201148
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