What are the radiotherapy and progress of cervical cancer?

Radiotherapy for cervical cancer (hereinafter referred to as radiotherapy) has been used for more than a century since the beginning of intracavitary radium therapy, and it is still one of the basic treatment methods for cervical cancer. Radiotherapy has a wide range of indications. It can be used for all stages of invasive cervical cancer, and for patients with carcinoma in situ who are not suitable for surgery. Radiotherapy can also be used for palliative treatment of advanced patients who are not suitable for radical radiotherapy to improve symptoms and prolong life. In recent decades, there have been many advances in radiotherapy technology for cervical cancer. The following is a brief description of the current status and progress of radiotherapy for cervical cancer.

1. Development of intracavitary radiotherapy technology

Intracavitary radium therapy has opened up a new era in the treatment of cervical cancer, but it has not solved the problem of doses for workers for a long time. Intracavitary afterloading technology, which began in the 1960s, has 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. This multifunctional afterloader is currently widely used in the radiotherapy of cervical cancer.

Traditional intracavitary treatment uses low-dose rate intracavitary treatment, which has been used for a long time and has accumulated a lot of experience. With the emergence of afterloading technology, high-dose rate intracavitary treatment has begun to be used in the radiotherapy of cervical cancer. Since high-dose rate treatment takes a short time, it is convenient for patients and increases the number of patients treated, so it is particularly popular in developing countries. At present, high-dose rate treatment is mostly used in China, and the radiation source mostly uses 192Ir sources that are easy to protect and have a short half-life. In addition, the miniaturization of the radiation source makes close-range treatment, especially interstitial implantation treatment, more convenient.

Among radioactive sources, the clinical application of 252Cf is a progress in recent years. 252Cf has been clinically applied as a neutron source for intracavitary radiotherapy in several countries and has been used for afterloading intracavitary radiotherapy. There are also clinical reports of 252Cf afterloading and its use in cervical cancer radiotherapy in my country.

2. Improvement of in vitro irradiation technology

External irradiation of cervical cancer can make up for the shortcomings of intracavitary treatment and increase the dose to the paracervical infiltration area and lymphatic metastasis area beyond point A. Over the past century, external irradiation therapy machines have gone through three stages from conventional X-ray therapy machines to 60 cobalt therapy machines to the current application of multiple accelerators. The continuous increase in energy has increased the deep dose, reduced the skin dose, improved the efficacy, and reduced the side effects. From the perspective of clinical use technology, in addition to vertical irradiation, there are also reports of rotation, pendulum and equal center technologies being used in cervical cancer radiotherapy. Moreover, with the development of computer technology and imaging technology, new technologies such as gamma knife, chi knife, three-dimensional conformal irradiation, and intensity-modulated therapy have emerged in recent years. These new technologies are still in the exploratory stage for the treatment of cervical cancer and cannot replace the current conventional radiotherapy combining external irradiation with intracavitary irradiation.

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

Different radiotherapy units use different machines and different radiotherapy methods. They have accumulated their own experience, but there are some common principles and issues that should be paid attention to in simple radiotherapy for cervical cancer:

1 Elimination dose Elimination dose refers to a dose given to an exophytic, large tumor to restore the cervix to a normal shape. Generally, vaginal treatment or tissue implantation is performed at the beginning of radiotherapy. The elimination dose can be used as a dose reference point 10 mm from the source, and the general elimination dose is 10 to 20 Gy. It should be noted that tumor elimination takes time, so at the beginning of treatment, the elimination dose is given during the whole pelvis irradiation, and when the whole pelvis irradiation is completed, the cervix shape is restored.

2. Pay attention to the dose to the uterine cavity. Although the clinical staging of cervical cancer is no longer based on whether the uterine cavity is invaded or not, the involvement of the uterine body is still common. It is reported that the uterine cavity is invaded in 7.8% of stage Ib, 25.5% of stage IIa, 38.2% of stage IIb, and the total involvement rate is 21.6%. Involvement of the uterine body is often accompanied by metastasis of lymph nodes and surrounding tissues, so the uterine body factor should not be ignored, and the dose to the uterine body should be paid attention to. 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.

3. 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 pelvic cavity, but is displaced laterally. At this time, the impact of intrauterine treatment on the parauterine dose 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.

4. Pay attention to the anatomical position of the uterine cavity and vagina. The normal uterine body 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 rate at the level of the uterine os, rectum, and bladder, which is beneficial to reducing complications.

5 Individual treatment: A certain plan may not be suitable for each specific case. It should be adjusted based on the above principles according to the patient's specific situation, treatment equipment and experience. For example, for early invasive cervical cancer, simple intracavitary radiotherapy is sufficient; for vaginal invasion and narrowness, cervical cavitation and inflammation, treatment starts with whole pelvic irradiation, and the whole pelvic irradiation dose can be increased, and the intracavitary treatment dose can be reduced accordingly; obvious vaginal invasive tumors or isolated metastases can be treated with vaginal plugs or molds; for cervical stump cancer, the external dose should be appropriately increased, and the intracavitary dose is reduced due to the lack of uterine volume. The specific dose is based on the length of the stump cervical canal, vaginal elasticity, lesions, and external irradiation methods and doses. For patients with ovarian tumors or inflammatory masses, surgical resection can be considered.

4. Combined treatment with radiotherapy and surgery

The combined treatment of radiotherapy and surgery includes preoperative irradiation and postoperative irradiation. The value of radiotherapy after radical hysterectomy for cervical cancer is still controversial. Some scholars believe that postoperative irradiation can improve the survival rate; but some scholars hold the opposite view, believing that postoperative irradiation not only cannot improve the survival rate, but also increases the incidence of serious complications. We believe that the surgical indications for cervical cancer should be strictly controlled, and inappropriate surgery should not be performed on some cases that are not suitable for surgery, and radiotherapy should not be used to "fill the hole". Of course, for some cases with poor prognostic factors such as pelvic or para-aortic lymph node metastasis or tumor thrombus in blood vessels and lymphatic vessels, and incomplete or suspected incomplete resection margins, auxiliary application of postoperative radiotherapy can be considered. Postoperative radiotherapy is mainly external irradiation, and those with cancer in the vaginal stump are treated intracavitary. It should be noted that the occurrence and severity of postoperative irradiation complications are related to the extent of surgery, radiation field area and dose.

Preoperative radiotherapy has received attention in recent years, mainly because some cases with poor prognostic factors, such as stage Ib2 cases with huge local tumors, have poor surgical efficacy alone. People have found that preoperative intracavitary radiotherapy can improve local conditions, reduce tumor size, and increase surgical resection rates. Since there are many complications after radical pelvic radiotherapy and extensive hysterectomy and pelvic lymph node dissection, in most units, preoperative radiotherapy is generally only given intracavitary treatment, and the dose is 1/3 to 1/2 of the full intracavitary radiotherapy. Since it takes a certain amount of time to eliminate the tumor, it is best not to perform surgery too early after radiotherapy and lose the significance of preoperative radiotherapy. If half the amount of intracavitary radiotherapy is given before surgery, surgery can be performed two weeks later.

5. Combination of radiotherapy and chemotherapy

In the combined treatment of radiotherapy and chemotherapy, two treatment methods, chemotherapy followed by radiotherapy (the so-called neoadjuvant chemotherapy) and concurrent radiotherapy and chemotherapy, have been studied more in recent years. Since cervical cancer lesions are mostly localized and cervical cancer is more sensitive to radiotherapy, and some clinical trials have not confirmed that neoadjuvant chemotherapy can improve the efficacy of cervical cancer radiotherapy, it is not recommended to routinely use neoadjuvant chemotherapy for cervical cancer patients undergoing cervical cancer radiotherapy. As for the scheme of using chemotherapy and radiotherapy simultaneously for the treatment of cervical cancer, many clinical trials abroad have shown encouraging conclusions, and many domestic institutions are currently conducting clinical observations of this treatment scheme.

The above is an introduction to "What are the radiotherapy and progress for cervical cancer?" For people who are related to the pathogenic factors of cervical cancer, it is recommended to take preventive measures against cervical cancer. If you have other questions about cervical cancer, please consult our experts online or call for consultation.

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