**Core Concept**
The preferred initial treatment for carcinoma of the anal canal involves a multidisciplinary approach that aims to preserve anal function and eliminate the tumor. This is typically achieved through a combination of chemotherapy and radiation therapy, which helps to shrink the tumor and control local disease.

**Why the Correct Answer is Right**
The standard treatment for anal canal cancer is chemoradiation, which involves administering a combination of chemotherapy and radiation therapy concurrently. This approach has been shown to be highly effective in controlling the local disease and preserving anal function. The chemotherapy agents used in conjunction with radiation therapy typically include 5-fluorouracil (5-FU) and mitomycin-C, which work synergistically to enhance the cytotoxic effects of radiation on tumor cells.

**Why Each Wrong Option is Incorrect**
**Option A:** Surgery is not the preferred initial treatment for anal canal cancer, as it can result in significant morbidity and may compromise anal function. While surgery may be necessary in certain cases, it is typically reserved for patients who have failed chemoradiation or have recurrent disease.
**Option B:** Hormonal therapy is not a standard treatment for anal canal cancer, as the disease is not hormone-sensitive. Chemoradiation is the preferred approach due to its ability to target rapidly dividing cancer cells.
**Option C:** Immunotherapy is not a standard treatment for anal canal cancer, although it may be explored in the context of clinical trials. The primary treatment approach for anal canal cancer remains chemoradiation.

**Clinical Pearl / High-Yield Fact**
Anal canal cancer is a rare but aggressive malignancy that requires a multidisciplinary treatment approach. The National Comprehensive Cancer Network (NCCN) guidelines recommend chemoradiation as the preferred initial treatment for anal canal cancer, reserving surgery for patients who have failed or are not candidates for chemoradiation.

**Correct Answer: C. Chemoradiation.