Anal cancer: Clinical sciences

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Introduction0:00–0:40

Anal cancer is a malignancy of the anal canal or perianal area. The two main subtypes of anal cancer include squamous cell carcinoma or SCC, which is the most common, and adenocarcinoma.
Although rare, the incidence of anal cancer has been increasing over the last decades likely due to the spread of human papillomavirus, or HPV, which is the number one cause of anal SCC.
Treatment depends on the histopathologic subtype as well as the stage of the cancer at the time of diagnosis. Alright, when a patient presents with a chief complaint suggestive of anal cancer, the first step is to obtain a focused history and physical.

History and Physical0:40–1:52

Typically, patients report rectal bleeding, anorectal pain, and the sensation of a mass within or around the anus. On further history, patients might have risk factors like previous or current HPV infection, HIV infection, immunosuppression, a high lifetime number of sexual partners, receptive anal intercourse, genital warts, or smoking.
Your examination should include a focused anorectal evaluation, including a digital rectal examination, or a DRE, and evaluation of the inguinofemoral lymph nodes.
DRE can reveal a hard, fixed, ulcerated mass in the perianal region or within the anal canal. Additionally, you might also find inguinal or femoral lymphadenopathy.
If you see these findings, you should suspect anal cancer. On exam, you might see anogenital warts, perianal skin irritation, or mucus or bloody discharge at the anal verge.Okay, now let’s talk about the initial work up when you suspect anal cancer.

Anoscopy + biopsy + FNA1:52–2:23

Your next step is to perform an anoscopy with biopsy of the lesion, and a fine needle aspiration or FNA of any clinically suspicious lymph nodes.
The anoscopy with biopsy can help you gain better visualization of the mass including its size and location, and provide pathologic confirmation of your diagnosis.
FNA can also confirm malignant nodal spread. Let's break this down further starting with squamous cell carcinoma.

Squamous Cell Carcinoma2:23–3:33

On anoscopy, you might see a tumor distal to the squamous mucocutaneous junction or in the hair-bearing skin. If the biopsy of the lesion or the FNA of a suspicious lymph node show malignant squamous cells, you can make your diagnosis of anal cancer squamous cell carcinoma or (SCC).
Once you have your diagnosis, your next step is to stage the cancer using the TNM system. This stands for Tumor size and location, lymph Node involvement, and presence of distant Metastasis.
To do this, first obtain a CT of the chest, abdomen and pelvis, MRI of the pelvis, and a PET scan. Additionally, if your patient is a biological female, a gynecologic exam with cervical cancer screening should be performed because of the close association of anal cancer and HPV infection.
Based on the imaging findings, you should be able to stage the cancer, which will guide your management. The first major element of staging you should focus on is the presence of distant metastases.
For patients with no distant metastases, your next step is to assess the location of the tumor. Now, if the tumor is located in the anal canal, you can treat with chemotherapy and radiation as the primary mode of therapy.

No Distant Metastases3:33–5:29

Most patients respond well to chemoradiation, so if they show complete clinical response, you can follow up with surveillance.
Surveillance includes evaluations with DRE, anoscopy, and an inguinal lymph node exam every 3 to 6 months; while CT of the chest, abdomen and pelvis and an MRI of the pelvis should be performed every year for 3 years.On the other hand, if the tumor is located in the perianal region, your next step is to stage the tumor to determine appropriate treatment.
For stage 1 lesions that are 2 cm or smaller in size and are well or moderately differentiated; or stage 2A lesions, which are between 2 to 5 cm in size and do not involve the sphincter, surgery should be consulted for wide local excision.
In cases where inadequate margins were obtained during surgery, patients may need re-excision or local radiation and chemotherapy.
If the margins are clear of malignancy or the patient responds well to chemoradiation, they can be followed up with surveillance.Alright, now let's talk about another subset of patients.
For patients with stage 1 cancer that are 2 cm or smaller but are poorly differentiated, or stage 2A lesions between 2 to 5 cm but that involve the sphincter, or stage 3 cancer, which includes any nodal involvement, the first line of treatment is chemotherapy with radiation.
Surgical resection is not recommended for these patients. Once your patient completes therapy and responds well, they can go on to surveillance.Let’s move forward and talk about patients who have distant metastases.
If the patient has evidence of metastatic disease, they have stage 4 anal cancer. The treatment includes systemic chemotherapy or chemoradiation to prevent disease progression, and make sure to offer palliative and supportive care, since the prognosis is poor for these patients.Okay, now that we have discussed anal squamous cell carcinoma, let's switch gears and talk about anal adenocarcinoma.

Distant Metastases5:29–5:54

Because adenocarcinoma arises from the glandular elements that are located within and proximal to the anal transformation zone, on anoscopy, you will find a tumor within the anal canal.

Adenocarcinoma5:54–6:55

If the biopsy of the lesion or FNA of any clinically suspicious lymph nodes show malignant glandular epithelial cells, you can confirm the diagnosis of anal cancer adenocarcinoma.Alright, once you have your diagnosis, your next step is to establish the TNM staging.
This is done with CT of the chest, abdomen and pelvis, MRI of the pelvis and PET scan. Similarly to SCC, if your patient is a biological female, a gynecologic exam with cervical cancer screening should be performed.
And again, one important aspect that determines treatment is the presence of distant metastases.Let’s first talk about patients without distant metastases.
For these patients, the mainstay treatment is surgical resection, so be sure to consult the surgical team. In addition, depending on the size of the tumor or lymph node involvement, neoadjuvant chemotherapy and radiation might be needed before surgical resection.
Patients with complete response will then go on to surveillance, which will include re-evaluation with DRE, anoscopy, and inguinal lymph node assessment every 3 to 6 months for 5 years.Let’s finish this topic with patients who have distant metastases.

No Distant Metastases6:55–7:27

Keep in mind, these patients are considered to have stage 4 disease. Although most patients with stage 4 cancer are not amenable for surgical resection, there is an exception for a specific subgroup of patients.
If a patient has a single isolated metastasis, most commonly found in the liver, they can be considered to have partially resectable disease.

Distant Metastases7:27–8:18

For these patients, you should first proceed with chemotherapy and radiation, then consult surgery for resection of the primary tumor and the isolated metastasis.
Once this is complete, patients can be followed up for surveillance of the primary tumor. On the other hand, patients who have unresectable disease should receive chemotherapy and radiation with a focus on palliative care, as the prognosis is very poor.Alright, as a quick recap… Anal cancer is a malignancy of the anal canal or perianal area, and the two main subtypes include squamous cell carcinoma or SCC and adenocarcinoma.
Anoscopy with biopsy of lesions and FNA of lymph nodes are needed for diagnosis, and treatment is based on TNM staging. For perianal SCC, stage 1 tumors that are well or moderately differentiated, or stage 2A tumors not involving the sphincter, treatment is surgical resection; while stage 1 but poorly differentiated, stage 2A involving the sphincter, or stage 3, as well as SCC of the anal canal, are treated with chemoradiation; and metastatic disease gets chemoradiation and palliative care.

Review8:18–9:24

For adenocarcinoma without metastasis, treatment includes surgical resection with or without neoadjuvant therapy; while resectable metastatic disease gets chemoradiation followed by surgical resection of both primary tumor and the metastasis; and unresectable metastatic disease gets chemoradiation and palliative care.
differentiated Stage two a involving the sphincter or as well as sc of the anal canal are treated with chemoradiation and metastatic disease gets chemoradiation and palliative care for adenocarcinoma without metastasis Treatment includes surgical resection with or without neoadjuvant therapy While resectable metastatic disease gets chemo radiation followed by surgical resection of both primary tumor and the metastasis An unresectable metastatic
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