Brachytherapy is a modality of internal radiation therapy used in cancer treatment, characterized by the placement of radioactive sources directly on or near the tumor. This technique allows high doses of radiation to be administered in a localized manner, minimizing damage to surrounding healthy tissues.
The use of brachytherapy has been extended to various neoplasms, such as prostate cancer, cervical cancer, breast cancer and skin cancer, demonstrating efficacy in tumor reduction and improving clinical results. In this blog, we will address the principles of brachytherapy by describing what brachytherapy is, the types of brachytherapy, its oncologic applications and recent advances that have optimized its safety and accuracy.
What is brachytherapy?
Brachytherapy is a modality of internal radiation therapy in which sealed radioactive sources are placed within or in close proximity to the tumor, allowing localized delivery of radiation. This procedure takes advantage of the principle of the inverse-square law, allowing high therapeutic doses to be delivered to malignant tissue with minimal exposure to adjacent healthy tissues.
It is used in the treatment of various types of cancer (breast, cervical, prostate, skin, etc.) and can be administered in low dose rate (LDR) or high dose rate (HDR) regimens, depending on the clinical indication and radiotherapeutic planning.
Types of brachytherapy
The classification of the different types of brachytherapy is based on the dose rate administered and the duration of radioactive implant placement. Below, we explain two of the main categorizations used in clinical practice.
High dose rate (HDR) versus low dose rate (LDR) brachytherapy
Brachytherapy can be classified according to the dose rate administered into high dose rate (HDR, High Dose Rate) and low dose rate (LDR, Low Dose Rate).
HDR brachytherapy uses high-activity radioactive sources, which allows the therapeutic dose to be administered in a short period of time, usually within minutes. This method is applied in several a single or a few sessions, which reduces treatment time and improves patient comfort. It is commonly used in cervical, prostate and breast cancer.
On the other hand, LDR brachytherapy uses lower activity radioactive sources, administering radiation continuously for prolonged periods, which can vary from several hours to days. It is mainly used in prostate cancer.
Permanent versus temporary implants
Another important classification of brachytherapy is based on the permanence of the radioactive implant. In permanent implant brachytherapy (LDR brachytherapy), small radioactive seeds, usually iodine-125 or palladium-103, are inserted into the tumor tissue and remain there indefinitely. Over time, the radioactivity of the seeds decreases to negligible levels. This technique is mainly used in the treatment of localized prostate cancer, allowing continuous irradiation of the tumor with minimal involvement of healthy tissues.
In contrast, brachytherapy with temporary implants (HDR brachytherapy) involves the placement of radioactive sources inside the body for a specific time and their subsequent removal once the prescribed dose has been administered. This modality is applied by means of catheters or specific applicators
In summary, brachytherapy comes in various modalities, each with specific indications depending on the type and location of the tumor. The choice between permanent or temporary implants depends on individual clinical factors, patient tolerance and personalized therapeutic planning.
How brachytherapy works: procedure, advantages and risks
The operation of brachytherapy is based on the proximity principle, which allows the delivery of high therapeutic doses with less impact on surrounding healthy tissues.
Procedure
The brachytherapy process is carried out in several stages. First, a detailed study of the patient’s anatomy is performed using medical imaging, such as magnetic resonance imaging or computed tomography, to plan the optimal placement of the radioactive source. Then, the radioactive materials are implanted through specific catheters or applicators, which can be done temporarily or permanently depending on the type of treatment. In the case of temporary implants, the radioactive source is removed once the prescribed dose has been administered, while in permanent implants, the radioactive seeds remain in the body and their activity progressively decreases over time.
Advantages
Brachytherapy has multiple benefits compared to other types of radiotherapy. Its main advantages include:
- High precision in radiation delivery, minimizing damage to healthy tissues.
- Shorter total treatment time compared to external beam radiation therapy.
- Reduced risk of long-term side effects in some types of cancer.
Risks and sequelae of brachytherapy
Although brachytherapy is an effective treatment, it is not without risks and possible adverse effects. Among the possible complications are inflammation and damage to nearby tissues, which can generate temporary symptoms such as pain, irritation or dysfunction of the treated organ. In some cases, sequelae of brachytherapy may occur, including fibrosis, alterations in the function of the affected organs and chronic discomfort. However, the risk of adverse effects depends on several factors, such as the location of the tumor, the dose administered and the patient’s individual response to treatment.
In conclusion, brachytherapy is a highly effective therapeutic modality that offers significant advantages in terms of precision and preservation of healthy tissues. However, adequate planning and medical follow-up is essential to minimize risks and manage the possible sequelae of treatment.
Brachytherapy for cancer treatment: applications and efficacy
Brachytherapy is a highly effective therapeutic strategy in multiple types of cancer, offering advantages in terms of precision, reduction of side effects and better quality of life for patients. Its application has been extended to several neoplasms, standing out in the treatment of prostate, breast and cervical cancer, among others that we will detail below. Furthermore, its use continues to evolve with technological advances that optimize its application and safety.
Prostate cancer
Brachytherapy is one of the most widely used therapeutic options for localized prostate cancer. There are two main modalities: low dose rate (LDR) brachytherapy, in which radioactive seeds are permanently implanted in the prostate gland, and high dose rate (HDR), in which radioactive sources are temporarily inserted. This technique offers significant advantages, such as a high rate of tumor control, less impact on sexual and urinary function compared to other treatments, and rapid patient recovery.
Breast cancer
Brachytherapy in breast cancer is mainly used as part of adjuvant radiotherapy after conservative surgery. Its most common use is accelerated partial breast brachytherapy (APBI), in which only tissues close to the tumor bed are irradiated, reducing exposure of the rest of the breast and neighboring organs. This technique reduces the duration of treatment compared to external radiation therapy and has demonstrated local control rates comparable to whole breast irradiation in selected cases.
Cervical cancer
Brachytherapy plays a crucial role in the treatment of cervical cancer, especially in locally advanced stages. It is used in combination with external radiation therapy and concurrent chemotherapy to improve tumor control and survival. The administration of high doses directly into the tumor allows eradication of malignant cells with a lower risk of toxicity to adjacent organs, such as the bladder and rectum. Intracavitary and interstitial brachytherapy are the most commonly used modalities in this type of neoplasm.
Other types of cancer
In addition to prostate, breast, cervical and endometrial cancers, brachytherapy has shown efficacy in the treatment of other neoplasms. In non-melanoma skin cancer, it is used as an alternative to surgery in selected patients, achieving good esthetic and therapeutic results. In head and neck tumors, such as those of the tongue and oral cavity, brachytherapy can be used as a primary or adjuvant treatment. It has also been used successfully in esophagus and some types of sarcomas, allowing focused radiation and preservation of the function of the surrounding tissues.
Finally, brachytherapy is a highly effective therapeutic strategy in multiple types of cancer, offering advantages in terms of precision, reduction of side effects and better quality of life for patients. As technologies and radiotherapeutic planning techniques advance, brachytherapy continues to consolidate its position as an essential treatment in the fight against cancer, with a promising future in terms of optimizing its safety and efficacy.