Gastrointestinal cancers

Esophageal cancer

Esophageal cancer is a malignancy that arises in the esophagus, the tube that carries food from the mouth to the stomach. For early-staged esophageal cancers ( small tumours without nodal spread), surgery alone is sufficient. When tumours are bigger or have spread to lymph nodes, chemotherapy and/or radiotherapy is necessary to reduce distant and local recurrence. Esophageal cancers are either adenocarcinoma ( more common in Western population) or squamous cell carcinoma ( more common in Asia). Squamous cell carcinomas are sensitive to chemo and radiotherapy, and in selected patients, surgery maybe omitted due to high response rates with chemoradiotherapy.

Here are some key points about concurrent chemoradiotherapy for esophageal squamous cell carcinoma:

1. Rationale:
   • Combining chemotherapy with radiation therapy is thought to enhance the treatment’s effectiveness by attacking cancer cells through different mechanisms.
   • The concurrent approach aims to maximize local control of the tumor and address potential micrometastases.
2. Treatment Plan:
   • Patients typically receive both chemotherapy and radiation therapy during the same time frame.
   • Chemotherapy drugs commonly used include cisplatin, 5-fluorouracil (5-FU), and taxanes. These drugs can enhance the effects of radiation on cancer cells.
3. Radiation Therapy:
   • External beam radiation therapy is the most common form used for esophageal cancer.
   • Radiation is focused on the tumor site and surrounding lymph nodes to destroy cancer cells and prevent them from dividing and growing.
4. Chemotherapy:
   • Chemotherapy drugs may be administered before, during, or after radiation therapy sessions.
   • The choice of chemotherapy drugs and their administration schedule may vary based on the specific characteristics of the tumor and individual patient factors.

However, since the esophagus is located close to the heart and lungs, traditional x-ray can increase the risk of side effects. Proton therapy is a potential treatment option for both operable and non-operable patients. Proton therapy may even be used if patients have had prior radiation for esophageal cancer.

Some trials could not find a survival advantage with proton beam therapy when compared with x-ray. Others reported that lung toxicities were less. A large study from South Korea with more than with more than a hundred patients found a high cure rate and safety with proton beam therapy. Overall survival at 5-years were about 80, 60 and 50% for stages I, II and III respectively. This finding was confirmed in a large meta-analysis of several separate clinical studies. 

 

 

Liver

 

Hepatocellular carcinoma is prevalent in Asia, due to high incidence of viral hepatitis. Proton therapy has emerged as a powerful tool in patients who are not suitable for resection, or choose not for liver transplants.

In the Korean 2022 guidelines, external beam radiotherapy is either a primary or alternative option in patients with certain stages of liver cancer. Proton therapy may be useful as it spares more healthy liver.

1. Precision Targeting: Proton therapy offers a more precise targeting of tumors compared to traditional radiation therapies. This precision is particularly beneficial for treating liver tumors, including hepatocellular carcinoma, as it allows for higher doses of radiation to be delivered to the cancer cells while minimizing damage to surrounding healthy liver tissue.
2. Reduced Radiation to Healthy Tissues: Unlike conventional radiation therapies, proton therapy has the ability to deposit the majority of its energy precisely at the tumor site and release minimal radiation beyond the target area. This characteristic is crucial when dealing with liver cancer, where minimizing damage to the surrounding healthy liver tissue is essential to preserve overall liver function.
3. Treatment of Challenging Tumor Locations: Proton therapy is especially advantageous for treating tumors located near critical structures or sensitive organs. In the case of HCC, where the liver is adjacent to vital structures, such as the stomach, intestines, and spinal cord, proton therapy allows for a more focused treatment, reducing the risk of damaging these neighboring structures.
4. Reduced Long-Term Side Effects: The precision of proton therapy contributes to fewer long-term side effects compared to traditional radiation treatments. This is significant in the context of hepatocellular carcinoma, as it may allow patients to maintain better liver function and overall quality of life during and after treatment.
5. Suitability for Specific Patient Profiles: Proton therapy may be particularly suitable for certain patients with hepatocellular carcinoma, such as those with larger tumors or tumors located in challenging anatomical locations. Individualized treatment plans can be developed to optimize the benefits of proton therapy for each patient.

It’s important to note that while proton therapy offers advantages, its availability may be limited, and decisions about the most appropriate treatment for hepatocellular carcinoma should be made based on a comprehensive evaluation by a multidisciplinary team of healthcare professionals. Other forms of local control include radiofrequency ablation, surgery, trans-arterial chemoembolisation and yittrium-90. 

 

Pancreas

Recommendations for RT for patients with pancreatic cancer are typically made based on a few clinical scenarios:

Borderline resectable  > to sterilise surgical margins

Locally advanced > ablative radiotherapy for longer term control

Palliative > coeliac plexus SBRT for pain relief, or local RT for symptoms

The goal of delivering RT is to sterilize vessel margins, enhance the likelihood of a margin-negative resection, and/or provide adequate local control to prevent or delay progression or prevent local disease recurrence while minimizing the risk of RT exposure to surrounding organs at risk (OARs). Radiation can also be used to palliate pain and bleeding or relieve obstructive symptoms in patients who have progressed or recurred locally.

 

Purpose:

• Shrink Tumors: Radiotherapy is used to shrink tumors that are close to major blood vessels, making them more operable.
• Control Disease Progression: Helps to control the growth of the cancer and potentially slow its spread.
• Alleviate Symptoms: Can be used to relieve symptoms such as pain by reducing the size of the tumor.

Types of Radiotherapy:

• External Beam Radiotherapy (EBRT): The most common type, where high-energy rays are directed at the tumor from outside the body. Proton beam therapy is an option for patient with inoperable tumours which are too large for SBRT.
• Stereotactic Body Radiotherapy (SBRT): Delivers highly precise radiation doses to the tumor, minimizing damage to surrounding tissues.

Treatment fractionations vary according to indication and type of radiotherapy.

For neoadjuvant chemoradiation, RT dose generally consists of 45–54 Gy in 1.8–2.0 Gy fractions.

For unresectable ablative radiotherapy, there are limited data to support a specific RT dosing for SBRT; SBRT doses of 3 fractions (total dose 30–45 Gy) or 5 fractions (total dose 25–50 Gy) have been reported.

More protracted courses delivering high doses through a hypofractionated approach (67.5 Gy in 15 fractions or 75 Gy in 25 fractions) are also acceptable. 

 

1. Treatment Delivery:

   • Sessions: Radiotherapy is typically delivered in multiple sessions over several weeks.
   • Positioning: The patient is carefully positioned for each session to ensure accurate targeting.
   • Radiation Delivery: High-energy radiation beams are directed at the tumor site. Each session lasts a few minutes, but the setup time can be longer.

2. Follow-Up and Monitoring:

   • Regular Imaging: To assess the tumor’s response to treatment.
   • Symptom Management: Ongoing evaluation and management of any side effects or complications from the treatment.
   • Adjustments: Modifications to the treatment plan may be made based on the tumor’s response and patient’s tolerance.

Side Effects of Radiotherapy in Pancreatic Cancer

Common Side Effects:

• Fatigue: General tiredness that may increase over the course of treatment.
• Nausea and Vomiting: Can occur due to the proximity of the treatment area to the stomach.
• Diarrhea: Radiation can affect the intestines, leading to gastrointestinal side effects.
• Skin Changes: Redness, irritation, and sensitivity in the treated area.

Less Common Side Effects:

• Abdominal Pain: Discomfort or pain in the abdomen.
• Loss of Appetite: Reduced desire to eat, potentially leading to weight loss.

Rare but Serious Side Effects:

• Radiation-induced Damage: To nearby organs such as the stomach, intestines, liver, or kidneys.

Radiotherapy plays a crucial role in the multidisciplinary approach to treating borderline and locally advanced pancreatic cancer, aiming to make tumors operable and to manage symptoms, thus improving patient outcomes and quality of life.