From the Guidelines
The Nigro protocol for anal cancer does actually include treatment of the inguinal lymph nodes. The standard Nigro protocol consists of combined chemoradiation therapy that targets both the primary anal tumor and regional lymph nodes, including the inguinal lymph nodes. Radiation fields typically encompass the primary tumor, perirectal, internal iliac, external iliac, and inguinal lymph nodes. The standard radiation dose is approximately 45-54 Gy, delivered concurrently with chemotherapy (typically 5-fluorouracil and mitomycin C) 1. Inguinal lymph node treatment is particularly important because anal cancer frequently spreads to these nodes, especially for tumors arising from the anal canal and lower rectum. Omitting inguinal lymph node treatment could lead to regional recurrence and compromise oncologic outcomes. The inclusion of inguinal lymph nodes in the radiation field is based on the lymphatic drainage pattern of the anal region and the high risk of microscopic disease in these nodal basins, even when they appear clinically negative on imaging studies. Some key points to consider when treating anal cancer with the Nigro protocol include:
- The incidence of inguinal nodal involvement increases with increasing primary tumour size and is at least 20% in patients with T3 disease 1.
- The risk is higher for primary tumours located below the dentate line or near the anal orifice, or in patients with N1 disease 1.
- Intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) is currently recommended for the treatment of anal cancer, setting strict RT dose constraints to normal organs 1.
- IMRT and VMAT allow for treatment with simultaneous integrated boost (SIB) and may reduce acute and late toxicity compared to conventional radiation therapy 1.
From the Research
Nigro Protocol for Anal Cancer
- The Nigro protocol is a standard treatment for anal cancer, which typically includes concurrent chemoradiotherapy with 5-fluorouracil (5-FU) and mitomycin-C (MMC) 2, 3.
- The protocol does not specifically mention the inclusion of inguinal lymph nodes, but it focuses on the treatment of the primary tumor and regional lymph nodes.
- Studies have shown that the Nigro protocol is effective in treating anal cancer, with high rates of progression-free survival, cancer-specific survival, overall survival, and colostomy-free survival 2, 4.
Inguinal Lymph Nodes
- Inguinal lymph nodes are not explicitly mentioned in the provided studies as part of the Nigro protocol for anal cancer.
- However, it is known that inguinal lymph nodes can be involved in the spread of anal cancer, particularly in cases with advanced disease.
- The treatment of inguinal lymph nodes may be considered on a case-by-case basis, depending on the extent of disease and other factors 5.
Chemoradiotherapy Regimens
- Various chemoradiotherapy regimens have been studied for the treatment of anal cancer, including 5-FU and MMC, as well as capecitabine and MMC 6, 4.
- These regimens have shown promise in treating anal cancer, with acceptable toxicity profiles and high rates of tumor control.
- The choice of chemoradiotherapy regimen may depend on individual patient factors, such as performance status and comorbidities 3, 5.