Radioactive seeds are implanted in some cancers as a form of internal radiation therapy called **brachytherapy**. This treatment involves placing tiny radioactive seeds directly inside or very close to the tumor, where they emit radiation over time to kill cancer cells while minimizing damage to surrounding healthy tissue. The seeds deliver a continuous, localized dose of radiation that targets the cancer precisely, which can be more effective and cause fewer side effects than external radiation beams.
The main reasons for implanting radioactive seeds in cancer treatment include:
– **Precision targeting:** By placing the radioactive material inside the tumor, the radiation affects cancer cells directly and intensely, sparing nearby healthy organs and tissues from excessive radiation exposure. This is especially important in sensitive areas like the prostate, cervix, breast, or vagina.
– **Continuous radiation delivery:** The seeds emit radiation steadily over weeks or months, allowing a sustained attack on cancer cells. This prolonged exposure can be more effective at destroying tumors than short bursts of external radiation.
– **Minimally invasive procedure:** Implanting seeds is usually done through a minimally invasive procedure guided by imaging techniques like ultrasound or mammography. This reduces recovery time and complications compared to more extensive surgery.
– **Organ preservation:** Because brachytherapy is so localized, it can often treat the cancer without removing or damaging the entire organ. For example, in prostate cancer, seeds can treat the tumor while preserving prostate function.
– **Improved outcomes and symptom relief:** Brachytherapy can cure certain cancers on its own or improve the effectiveness of surgery and chemotherapy. It can also shrink tumors to relieve symptoms like pain or bleeding.
How it works in practice: During the procedure, doctors use imaging tools to guide the placement of many tiny radioactive seeds into the tumor. These seeds contain radioactive isotopes such as iodine-125 or palladium-103, which emit radiation that penetrates and destroys cancer cells nearby. The radiation gradually diminishes as the isotopes decay over time, and the seeds themselves remain permanently implanted but become inactive.
This method is commonly used for cancers such as:
– **Prostate cancer:** Permanent seed implantation is a standard treatment option. Ultrasound guides the placement of seeds inside the prostate, delivering radiation over several months to kill cancer cells while sparing surrounding tissues.
– **Breast cancer:** Radioactive seeds can be used to localize tumors before surgery or as part of internal radiation therapy to target residual cancer cells.
– **Gynecological cancers:** In cancers of the cervix, uterus, or vagina, brachytherapy delivers high doses of radiation internally, which can be more effective and less harmful than external radiation alone.
– **Other tumors:** Some head and neck cancers and neuroendocrine tumors may also be treated with radioactive seeds or similar internal radiation techniques.
Compared to external beam radiation, brachytherapy with implanted seeds offers a more focused, intense, and sustained radiation dose directly to the tumor, reducing side effects and improving treatment precision. It also allows for outpatient procedures and faster recovery.
In summary, radioactive seeds are implanted in some cancers because they provide a highly targeted, effective, and minimally invasive way to deliver radiation directly to tumors, improving cancer control while preserving healthy tissue and organ function. This approach has become an important tool in modern cancer treatment, especially for tumors located in sensitive or hard-to-reach areas.