Radiotherapy for cervical cancer

Radiotherapy for cervical cancer has been used for more than a century, starting with intracavitary radium therapy, and is still one of the basic treatments for cervical cancer. Radiotherapy has a wide range of indications, and can be used for all stages of invasive cervical cancer, including radical radiotherapy and palliative radiotherapy.

1. Intracavitary radiotherapy Intracavitary radium therapy has created a new era for the treatment of cervical cancer, but it has not solved the problem of radiation exposure for workers for a long time. The intracavitary afterloading technology that began in the 1960s solved the problem of worker protection. Afterloading therapy has evolved from manual afterloading to mechanical control to today's computer-controlled multifunctional afterloading therapy machine with a treatment planning system. The multifunctional afterloader makes high-dose rate intracavitary therapy applicable to the radiotherapy of cervical cancer.

The high-dose rate therapeutic radiation sources currently used in China are mostly easy-to-protect and short-half-life radiation sources. In addition, the miniaturization of radiation sources makes close-range treatment, especially interstitial implantation treatment, more convenient.

2. External irradiation of cervical cancer External irradiation of cervical cancer can make up for the shortcomings of intracavitary treatment and increase the dose to the paracervical infiltration area and lymph node metastasis area. Over the past century, external irradiation therapy machines have gone through three stages from conventional X-ray therapy machines, drill therapy machines to the current application of various accelerators. Due to the continuous increase in energy, the deep dose is increased, the skin dose is reduced, the efficacy is improved, and the side effects are reduced. From the perspective of clinical use technology, in addition to vertical irradiation, rotation, pendulum and isocentric technologies have also appeared. Moreover, with the development of computer technology and imaging technology, new technologies such as the scalpel, X-knife, three-dimensional conformal irradiation, and intensity-modulated therapy have emerged in recent years, making radiotherapy indications more extensive.

3. Issues that should be noted in simple radiotherapy for cervical cancer

(1) Pay attention to the dose to the uterine cavity. Although the clinical staging of cervical cancer is no longer based on whether the cervical cavity is invaded or not, it is still common for cervical cancer to involve the uterine body. Involvement of the uterine body is often accompanied by metastasis to the lymph nodes and surrounding tissues. Therefore, the uterine body factor should not be ignored, and attention should be paid to the dose to the uterine body. If only the dose to the cervix and paracervix is ​​considered, and the dose to the uterine body is ignored, it may easily lead to uterine body recurrence.

(2) Uterine displacement Uterine displacement is common in clinical practice. Due to certain reasons, such as inflammation, tumors, pelvic surgery, etc., the uterus is often not located in the middle of the pelvic cavity, but is displaced laterally. At this time, the impact of intrauterine treatment should be considered (the dose on the far side is reduced, and the dose on the displaced side is increased). The cause of the displacement should be carefully analyzed, and the external dose should be adjusted to compensate for the impact on the parauterine dose.

(3) Pay attention to the anatomical position of the uterine cavity and vagina. In normal cases, the uterus tilts forward and the uterus and vagina form a certain angle. The effect of this factor on the dose and distribution should be considered during treatment. Treating the uterine cavity and vagina separately can reduce this effect and reduce the dose at the level of the cervical os, rectum, and bladder, which is beneficial to reducing complications.