Brachytherapy for Rectal Cancer
Rectal cancer surgery is complicated by the proximity of the rectum to other organs and structures. Patients often have to make the difficult choice between radical resection, which requires subsequent use of a stoma, or sphincter preservation surgery that maintains quality of life but carries a higher risk of recurrence. Brachytherapy for rectal cancer is now available as a potential alternative to surgery for patients with low-lying small rectal tumors.
What is rectal cancer?
Rectal cancer is the development of malignant cells in the tissues of the rectum, the last section of the large intestine that meets the anal canal. It is characterized by changes in bowel habits and the appearance of blood in the stool. The rectum and anal canal combined are 6‑8 inches long and the position of the tumor can influence the treatment strategy. In about a third of cases, rectal tumors are low-lying, i.e., located no more than 6 cm from the anal verge, and thus are more easily accessible.
Survival rates have improved significantly in recent years, with an overall 5-year survival rate of 64%1.
Standard Rectal Cancer Treatments
Irrespective of the stage of rectal cancer, the most common treatment is surgery. The extent of the surgery depends on the degree to which the tumor has spread into the surrounding tissue. Sometimes, if the cancer is detected early, a polypectomy may suffice, but a full resection is often required. This removes the rectum’s cancerous section and some surrounding healthy tissue2. Typically, the lymph nodes are also removed to reduce the risk of the cancer cells spreading to other parts of the body.
Many patients undergoing rectal resection will require a stoma that diverts fecal waste to an external bag rather than being expelled through the anus. If the anus does not need to be removed, this may be reversible but can impinge significantly on the patient’s quality of life.
Brachytherapy for rectal cancer is an emerging radiation treatment that can improve treatment options for some patients.
Why Brachytherapy is Beneficial for Rectal Cancer
Brachytherapy for rectal cancer involves contact radiation and obviates the need for surgery and insertion of a stoma3.
Standard radiotherapy is commonly used before surgery to reduce the tumor, so it is easier to excise and prevent cancer from coming back after surgery. Standard radiotherapy is administered by an external beam, so the radiation must pass through the skin and intervening tissue to reach the tumor.
High-dose brachytherapy utilizing isotopes such as IR192 is now being used to treat small low-lying rectal cancers4,5. The Papillon technique uses Low energy, high-dose X-ray brachytherapy for the treatment of rectal cancer and involves limited targeted radiation being applied directly to the tumor from inside the rectum6. Such contact radiation prevents the risk of tissue damage and other side effects of traditional radiotherapy. Furthermore, brachytherapy, including Papillon X-ray brachytherapy allows a higher dose of radiation to be applied to the tumor, increasing the effectiveness of the radiotherapy.
Brachytherapy for rectal cancer is given on an outpatient basis and requires minimal local anesthesia7. Therefore it prevents the risks associated with surgery and makes treatment possible in patients who are unable to undergo general anesthesia. It has the added advantage of avoiding the need for stoma formation. Both Papillon and HDR Brachytherapy provide a potential treatment option for colorectal cancer patients not eligible or willing to undergo resection.
Papillon X-ray brachytherapy for rectal cancer is also known as contact radiotherapy and can be used as a pre-external bean treatment of tumors <3 cm in diameter or post long course chemoradiotherapy rectal cancer for tumors <5cm in diameter that shows no evidence of lymph node spread. It offers eligible patients an alternative to major surgery and permanent stoma, whilst having the potential to cure rectal cancer.
References
- American Cancer Society. https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/survival-rates.html
- National Cancer Institiute. https://www.cancer.gov/types/colorectal/patient/rectal-treatment-pdq#_92
- Vuong T, Devic S. J Contemp Brachytherapy. 2015;7(2):183-188.
- Garant A, et al. Clinical Investigation 2019;105,5:1005-1011.
- Buckley H, et al. Int J Radiat Oncol Biol Phys. 2017;99(1):111-127.
- Papillon J. Dis Colon Rectum. 1974;17:172–180.
- The Clatterbridge Cancer Centre. https://www.clatterbridgecc.nhs.uk/patients/treatment-and-support/papillon