Cervical cancer is the most common gynecologic malignancy, and the reasonable choice of its treatment is directly related to the prognosis of patients. The basic treatment methods for cervical cancer are radiotherapy and surgery. In recent years, chemotherapy has made great progress, but it is not yet the first choice for radical treatment. In recent years, chemotherapy has made great progress, but it is not the first choice of curative treatment. Radiation therapy for cervical cancer has satisfactory efficacy and the 5-year survival rate of stage I reaches 90%, which is easy to master and carry out. Therefore, as a clinical gynecologic oncologist, it is very important to master the basic theories and principles related to radiotherapy. In the following, this article will give a preliminary introduction to the “internal and external” radiotherapy for cervical cancer.
I. What are the types of radiotherapy for cervical cancer and what are the technical differences?
Radiotherapy for cervical cancer can be divided into distant radiotherapy (external radiation) and brachytherapy (intracavitary radiation). In external radiation, the radiation source is located at a certain distance outside the body and concentrates on a certain part of the body; in intracavitary radiation, the radiation source is placed inside the uterine cavity or vagina for treatment. The two are different in terms of technology.
1.Extracorporeal irradiation mainly uses conventional technology, isocenter technology and conformal technology/intensity adjustment technology.
(1) Conventional technique.
Conventional techniques for extracorporeal irradiation of gynecologic tumors include whole pelvic irradiation, vertical irradiation of the four pelvic fields, parietal aortic extension field, inguinal irradiation field, whole abdomen irradiation, supraclavicular field irradiation, etc. For example, the design scope of pelvic irradiation field external irradiation scheme includes pelvic organs and lymphatic drainage area. Full pelvic field location: the upper boundary is flat at the lower edge of the 5th lumbar vertebra, the lower boundary is flat at the lower edge of the closed foramen, and both sides of the anterior and posterior fields reach the inner 1/2 of the femoral head. central lead blocking field (pelvic four small fields): on the basis of the full pelvic field, the central lead is blocked to obscure the bladder and rectum, so that the two pelvic anterior and posterior fields are changed to pelvic four small fields.
(2), Isocenter technique
Isocenter technique makes the center of tumor coincide with the rotation center of radiotherapy equipment during radiotherapy, and uses various indication devices of radiotherapy equipment to realize the requirements of radiotherapy plan, which greatly improves the positioning and positional accuracy. This technique is an important technique in the treatment of deep tumors. It is especially suitable for mass tumors, and is not applicable to sheet tumors, especially those in superficial areas. The isocentric technique is characterized by patient comfort during treatment, accurate positioning, and rapidity. This technique is actually a complete process, including a series of processes such as tumor localization, positioning, and dose treatment, etc. The hardware part of this technique consists of laser localization lamp, simulator, and isocenter radiotherapy machine. Its software part has positioning and positional techniques, dose analysis and treatment methods.
(3) Conformal technology/intensity modulation technology
Conformal therapy, also known as three-dimensional therapy, is characterized as an irradiation technique adapted to the shape of the tumor, which can increase the dose to the tumor due to the smaller amount of normal tissue surrounding the tumor, thus potentially improving survival rates and reducing complications. The shape-adapted technique requires attention to obscure the bladder, rectum and avoid the spinal cord when appropriate. Intensity-modulated radiotherapy technique can be directly applied to the spinal cord, small intestine, bladder, rectum, liver, kidney and other dangerous organs in a limited amount before the reverse plan than conventional conformal technique, which can play an obvious protective role, and can synchronize the tumor area to increase the dose, which has been gradually and widely used in clinical practice.
2.Internal irradiation used to place radium into the uterine cavity and vagina to treat the primary foci of tumor and adjacent affected areas. However, this method is not in line with the principle of staff protection, so people invented the method of post-loading treatment. Post-loading treatment involves placing an empty container without a radioactive source at the treatment site, and then delivering the radioactive source into the container for irradiation by manual or mechanical action. Modern post-loading treatment machines have developed into remote controlled, computerized, multifunctional treatment machines.
Intracavity treatment usually uses point A as the dose reference point. According to the size of the A-point dose rate intracavity afterloading can be divided into high dose rate (A-point dose rate > 12Gy/h), low dose rate (A-point dose rate of 0.4-2Gy/h) and medium dose rate (A-point dose rate of 2-12Gy/h) treatment. China basically adopts high dose rate afterloading treatment, which is characterized by short treatment time and easy protection.
II. Which patients need radiotherapy?
Cervical cancer has a wide range of indications and all stages can be treated with radiation therapy.
(1) Stage IA Surgery is preferred, and radiotherapy can be given to those who cannot be operated.
(2), Stage IB, IIA Radical surgery or radical radiotherapy.
(3), for barrel cervical cancer, chemotherapy is preferred before deciding on surgery or radiotherapy.
(4), Stage IIB-IVA Radiotherapy is the mainstay, and sensitization chemotherapy can improve the efficacy.
(5), Stage IVB Palliative treatment.
(6) Those who have severe anemia before radiotherapy should be corrected, and those who have infection should control the infection.
C. Which patients are not suitable for radiotherapy?
However, not everyone is suitable for radiotherapy. While radiotherapy kills cancer cells, it can also cause damage to normal tissues and produce toxic side effects. Patients with the following diseases should not undergo chemotherapy.
(1), bone marrow suppression, total peripheral blood leukocytes <3×10^9/L and platelets <70×10^9/L.
(2), extensive tumor, cachexia, uremia.
(3), acute or subacute pelvic inflammatory disease.
(4), severe hepatitis, tuberculosis, uncontrolled cardiovascular disorders and psychotic episodes.
(5) If cervical cancer is combined with ovarian tumor, the ovarian tumor should be removed before radiotherapy is administered.
Which patients should have preoperative radiotherapy?
Pre-operative radiotherapy can shrink the tumor and eliminate the subclinical lesions around the tumor, so that the scope of surgery can be reduced and patients who cannot be operated before radiotherapy can get the chance to operate. Meanwhile, preoperative irradiation can reduce tumor cell viability and possibly reduce implantation and metastasis due to surgery. It is suitable for: ①, stage Ib2 cervical cancer with larger exophytic tumor; ②, stage IIa cervical cancer involving more vagina; ③, pathology of stage III; ④, mucinous adenocarcinoma and squamous adenocarcinoma; ⑤, barrel-shaped cervical cancer.
V. Do I need radiotherapy after radical surgery? Which one to choose?
Supplementary external irradiation or intracavitary afterloading treatment is given after radical surgery, with the purpose of continuing to eliminate residual lesions, controlling disease development and improving treatment effect. It is suitable for: ①, large primary tumor, deep infiltration and vascular tumor embolism; ②, metastasis of pelvic lymph node cancer; ③, infiltration of parametrial tissue; ④, positive cut margin with residual cancer. Postoperative pathology with high-risk factors requires 45-50 Gy of external pelvic irradiation (for conventional, three-dimensional conformal techniques need to shield rectum and bladder after 40 Gy) and 10-20 Gy of internal irradiation of the vaginal stump, combined with simultaneous sensitization chemotherapy if necessary. If the lymph nodes of abdominal aorta metastasize, expanded field irradiation is required.
VI. How to choose intracavitary and extracavitary radiotherapy for cervical cancer?
The reasonable combination of intracavitary radiotherapy and extracorporeal irradiation is the key to successful radiotherapy for cervical cancer. Intracavitary radiotherapy mainly targets the primary focus, while extracorporeal irradiation irradiates the infiltrated area around the tumor and lymphatic metastasis area to make up for the shortage of intracavitary treatment. According to the dose of intracavitary and extracorporeal irradiation given to point A, there are roughly 3 types, namely.
(1), intracavitary radiotherapy mainly, supplemented by extracorporeal irradiation; traditional standard radiotherapy for cervical cancer and inherited post-mounted treatment mostly adopt this method.
(2) Extracorporeal irradiation mainly, supplemented by intracorporeal radiotherapy; this method is superior for advanced cervical cancer with severe parametrial infiltration or more vaginal infiltration and vaginal stenosis.
(3).Intracavitary and extracorporeal are both important. This method is mostly used for post-mount treatment of cervical cancer with high dose rate in China. There are three ways of implementation, i.e. extracorporeal followed by intracorporeal, intracorporeal followed by extracorporeal and both at the same time. The use of ex vivo followed by intracorporeal is beneficial for those with pelvic infection and those with altered pelvic anatomy due to tumor, but the procedure is longer and may result in vaginal stenosis, increase the difficulty of intracorporeal radiotherapy and affect the dose distribution. The use of intracavitary followed by extracorporeal treatment results in rapid local tumor elimination, rapid control of symptoms (e.g., bleeding), and subsequent improvement of the patient’s condition, but is prone to infection. The method of simultaneous intracorporeal and extracorporeal treatment takes into account the advantages of both of the above-mentioned methods and is beneficial to the treatment, so it is mostly used.
After repeated clinical practice, our ideal radiotherapy plan for cervical cancer at this stage is designed as follows: whole-pelvic irradiation is applied first, followed by simultaneous high-dose rate intracavitary rear-loading radiotherapy and pelvic four-field irradiation. After the pelvic four-field irradiation, the remaining intracavitary afterload radiotherapy is completed. Total pelvic external irradiation, DT 3000 cGy for about 3 weeks, once daily at 180 cGy per DT, 5 times a week (Monday to Friday). Pelvic four-field irradiation, DT1500-2000cGy, 1 time daily, each DT180cGy, 4 times a week (intracavitary treatment on 1 out of 5 days in 1 week). Intracavitary therapy: vaginal cassette and cervical canal therapy are performed simultaneously or separately, once a week, with a dose of 5-6 Gy at each A site and a total of 35-40 Gy at A. In the course of radiotherapy for cervical cancer, external irradiation is responsible for the irradiation of parametrial tissues and regional lymph nodes, while intracavitary therapy is mainly responsible for the primary tumor and adjacent parametrial tissues, especially because of the anatomical peculiarities of the cervix and the inverse square law of dose decay of intracavitary therapy In particular, the anatomical peculiarities of the cervix and the inverse square law of intracavitary treatment dose decay make it possible to obtain more than 100 Gy of local irradiation to the cervix. The reasonable combination of brachytherapy and distant irradiation is the reason for the more ideal efficacy of radiotherapy for cervical cancer.
7. Should I use intracavitary or extracorporeal radiotherapy if I have inflammation?
Cervical cancer is often combined with local tumor infection, and some patients have underlying pelvic infection, which is often aggravated during radiotherapy, especially intracavitary irradiation. Therefore, patients with combined inflammation can start from whole pelvic irradiation, and the dose of whole pelvic irradiation can be increased and the dose of intracavitary treatment can be reduced accordingly.
What is intensity-modulated radiation therapy? Who is it suitable for?
Intensity-modulated radiotherapy is a kind of three-dimensional conformal radiotherapy, which requires the dose intensity in the radiation field to be adjusted according to certain requirements, referred to as intensity-modulated radiotherapy. The dose distribution in a single radiation field is not uniform, but the dose distribution in the whole target volume is more uniform than that of 3D conformal therapy. The intensity modulation technique can directly treat the spinal cord, small intestine, bladder, rectum, liver, kidney and other dangerous organs in a limited amount before the inverse plan, which plays an obvious protective role, and can synchronize the dose addition in the tumor area, which has been gradually and widely used in clinical practice. Intensity modulated radiation therapy is also not a panacea, and there are almost always some limits in the development of intensity modulation plans, and some degrees of dose distribution cannot be truly achieved. In addition, due to the limitation of mathematical formula, or due to the limitation of computer speedometer time, as well as the patient’s daily relevant treatment location, internal anatomical location changes, etc., so the use of intensity modulation technology at this stage still needs to be extra careful to reduce the error.
IX. What are the common complications after radiotherapy and how to deal with them?
The reactions caused by radiation therapy for cervical cancer are divided into immediate and long-term reactions, with rectal and bladder reactions being the most obvious. Radiotherapy reactions are inevitable in radiotherapy, but it is necessary to avoid causing radiation damage.
1.Recent reactions Recent reactions refer to the reactions occurring in radiotherapy or within 3 months after radiotherapy.
(1) Systemic reactions: headache, dizziness, weakness, loss of appetite, nausea, individual patients have vomiting. White blood cells and platelets are mildly decreased. Systemic reactions are more severe in combination with chemotherapy. The degree of reaction is related to age, general condition and other factors. Generally symptomatic treatment, more can continue radiotherapy.
(2) Rectal reaction: It mostly occurs 2 weeks after the start of radiotherapy, and almost all patients will have different degrees of reaction. The main manifestations are acute and severe reaction, diarrhea, mucus stool, painful stool and blood in stool, and the reaction is more serious for combined hemorrhoids. Patients may be advised to use high-protein, multivitamin, easily digestible food. Treat symptomatically with antidiarrheal medications such as loperamide, hexadecagonal montelukast, bifidus triptans, etc. In severe cases, suspend radiotherapy and resume irradiation when symptoms improve.
(3) Bladder reaction: mostly occurs 3 weeks after the start of radiotherapy, manifested as urinary frequency, urinary urgency, urinary pain, and some may have hematuria. Improve after anti-inflammatory and hemostatic treatment. In severe cases, radiotherapy is suspended.
(4) Internal irradiation-related reactions: 1. bleeding and pain during operation, mostly not serious, if bleeding is more available hemostatic drugs or gauze filling. 2. low incidence of uterine perforation, in order to further reduce its incidence and reduce the incidence of the resulting intestinal fistula and enterocolitis, it is recommended that gynecological examination and film reading before operation, careful operation, once the exploration of the uterine cavity is too deep and “bottomless When the cavity is too deep and “bottomless”, stop the operation immediately. For suspected perforation to perform ultrasound, CT clear, remove the sender or reduce the residual position, reduce the dose of treatment, the patient in a semi-recumbent position, antibiotics to prevent infection.
(5), vulvodynia: due to the stimulation of vaginal discharge and the influence of radiation, it is easier to have different degrees of radiation reaction in the vulva, should keep the local clean and dry, protect the trauma and promote healing.
(6), vaginitis: radiation, especially intracavernous irradiation, can cause physical inflammatory reaction of the vagina, which is manifested by edema, congestion, pain and increased discharge of vaginal mucosa, and vaginal douching should be strengthened and local antibiotics should be applied.
2. Long-term complications The patient’s combination of diabetes, hypertension or history of pelvic disease surgery may increase the possibility of long-term complications.
(1) Radiation cystitis: it occurs mostly about 1 year after radiotherapy, mainly manifested as urinary frequency, urinary urgency and urinary pain. In severe cases, there is vesicovaginal fistula. For mild to moderate radiation cystitis, the main treatment is conservative, anti-inflammatory, hemostatic, keeping the bladder empty, and bladder irrigation with saline + antibiotics + hemostatic drugs. Surgery in severe cases.
(2), radioactive small bowel infection: any cause of abdominal and pelvic small bowel fixation can aggravate the radiation damage to the small intestine, manifested as dilute stool, increased stool frequency, mucus stool, abdominal pain, etc., which can be treated symptomatically. In severe cases, the small intestine has perforation and obstruction, requiring surgery.
(3), pelvic fibrosis: high-dose whole pelvic irradiation may cause pelvic fibrosis, secondary to ureteral obstruction and lymphatic obstruction in severe cases, leading to hydronephrosis, renal dysfunction and lower limb edema. Chinese herbal medicine that activates blood circulation and removes blood stasis is available. Ureteral stenosis and obstruction require early surgical treatment.
(4), vaginal stricture: it is recommended to perform vaginal douching for six months after radiotherapy, at an interval of 2-3 days, and wear vaginal molds if necessary. It is recommended to start sexual life 3 months after radiotherapy.
(5) Radioactive proctitis and sigmoid colitis: they often occur six months to one year after radiotherapy, and the main symptoms are diarrhea, mucus stool, urgency, blood in the stool, and sometimes constipation. In a few cases, rectal stricture may occur, and in severe cases, rectovaginal fistula may result. Treatment is mainly anti-inflammatory, hemostatic and symptomatic, with the addition of vitamin C, vitamin E, vitamin A. Enemas can be reserved with enema combination (tincture of opium, tincture of belladonna, prednisone, bryony gum syrup, epinephrine). Chinese herbal medicine can also be used to clear heat and detoxification, anti-inflammatory and pain relief, astringency and hemostasis, and benefit of Qi. In case of rectal stricture, obstruction, fistula, perforation, surgery will be considered.
X. Care and precautions before and after radiotherapy?
1.Psychological care
Most patients with cervical cancer cannot understand their disease correctly, have great stress in their mind, have fear of disease and lose confidence in life. Nursing staff must do a good job in the ideological work of patients seriously and carefully before treatment, so as to reduce patients’ ideological pressure and fear psychology, increase patients’ trust and enhance their confidence to survive.
2.Do a good job of health education guidance before radiotherapy
Most patients lack understanding and knowledge of radiotherapy. Before treatment, we should introduce the purpose of treatment, efficacy, course of treatment, precautions for treatment and possible adverse reactions to patients and their families in detail, and sign the informed consent form and issue the treatment guideline pamphlet, so that they can have certain understanding and psychological preparation, eliminate the fear of treatment and facilitate They should accept the treatment happily and cooperate with it actively.
3.Dietary guidance and care for patients before radiotherapy
Before radiotherapy, we should understand the patient’s physical condition and nutritional status in detail, give high protein and high vitamin diet, eat more shiitake mushrooms and black fungus to increase the immune function of the body, avoid gas-producing foods such as beans and milk, and avoid spicy and stimulating foods.
4. Care of vaginal douching
(1) Importance and purpose of vaginal douching.
Most of the patients with cervical cancer are in the middle or late stage, they have irregular vaginal bleeding and vaginal discharge, and the cancerous tissues can produce pulpy secretion when they break down. The purpose of vaginal douching: to remove necrotic detached tissues, reduce infection, promote local blood circulation, improve the nutritional status of tissues, avoid vaginal adhesions, and facilitate the absorption and remission of inflammation; meanwhile, it can remove necrotic tissues after radiotherapy, improve the sensitivity of radiotherapy, and prevent pelvic peritonitis.
(2) Douche method: general patients should be douched with 1:5000 potassium permanganate solution once a day, and for patients with more secretions and strong odor, vaginal douche twice a month; douches should be prohibited for those with heavy bleeding, and the douches should be gentle, with moderate douche pressure and appropriate temperature, and the sterilization isolation system and aseptic technique should be strictly implemented to prevent cross-infection.
5. Care of radioactive proctitis
Radiation proctitis is one of the early complications of radiation therapy for cervical cancer, which can be divided into mild, moderate and severe degrees according to the severity, and the incidence varies according to the treatment mode and total radiation dose, about 10%-20%. As the number of radiotherapy increases, some of them have rectal reactions, which are manifested as acute posterior and blood in stool, etc. Compound procaine enema (0.25% procaine 200ml plus gentamicin 80,000 units, prednisone 10mg plus 1% epinephrine 1~2ml) is available, once in the morning and once in the evening, and the nature of stool is closely observed to prevent water-electrolyte disorder and aggravate systemic support therapy.
6.Guidance on the health of patients after radiotherapy
In vitro radiotherapy patients should keep the irradiated field skin clean and dry to prevent infection; avoid hot and cold compresses and soap scrubbing on the irradiated field skin, minimize friction with rough clothes and scratching with hands; insist on vaginal douche once a day for 6 months after intracavitary post-radiotherapy; within 6 months after radiotherapy, patients are advised to avoid sexual life because the trauma is not healed.