Cancer pain: a comprehensive approach to treatment

Types of cancer pain

Pain in cancer patients can have different origins and characteristics, and understanding them well is key to treating them correctly. The main categories:

• Pain from the tumor itself: tissue invasion, compression of neighboring structures, infiltration of nerve plexuses, bone metastases.
• Pain from treatments: chronic post-surgical pain (mastectomy, thoracotomy), chemotherapy-induced neuropathy, radiation-related pain, mucositis.
• Pain in survivors: patients who have completed cancer treatment but are left with painful after-effects (residual chemotherapy-induced neuropathy, post-surgical pain, post-radiation fibrosis).
• Breakthrough pain: episodes of intense pain that flare up over well-controlled background pain. It requires a specific rescue-medication plan.

Most patients have mixed pain: a nociceptive component (from tissue damage) and a neuropathic component (from nerve involvement). That is why treatment usually requires combining strategies.

An important nuance: in cancer pain, opioids have a clear role — indicated and endorsed by every international guideline. Fear of dependence does not carry the same weight in this context as in other settings, and it often ends up hurting the patient. Properly prescribed, with gradual dose escalation, monitoring of side effects, and combined with other measures, opioids provide a level of pain control that completely changes the experience of the illness. The WHO analgesic ladder remains a useful guide, always adapted to each patient.

The stepwise pharmacological approach

Decades ago, the WHO established an "analgesic ladder" for cancer pain that remains the foundation of treatment, with modern updates:

• Step 1: mild pain. Acetaminophen (paracetamol) or NSAIDs (with precautions, especially in patients with cardiovascular, gastrointestinal or kidney risk).
• Step 2: moderate pain. Weak opioids (tramadol, codeine), alone or combined with acetaminophen/NSAIDs.
• Step 3: severe pain. Strong opioids (morphine, oxycodone, fentanyl, methadone). Doses are titrated according to response and tolerance.

Added to this are adjuvants chosen by pain type: gabapentinoids and antidepressants for the neuropathic component, corticosteroids in certain situations (spinal cord compression, raised intracranial pressure, plexus infiltration), bisphosphonates or denosumab for metastatic bone pain, antispasmodics for visceral pain.

The fundamental rule: treat pain on a regular, preventive schedule (not as-needed), with a baseline regimen and rescue doses available for breakthrough pain. Well-controlled pain significantly improves tolerance to cancer treatment and quality of life.

When to add interventional treatment

When medication alone does not adequately control the pain, or when side effects limit the doses needed, interventional procedures can significantly change the picture. The most relevant options:

• Celiac plexus block: for pain from pancreatic cancer and other upper abdominal tumors. It is one of the procedures with the strongest evidence in cancer pain.
• Superior hypogastric plexus block: for cancer-related pelvic pain.
• Ganglion impar block: for perineal pain.
• Intercostal and paravertebral blocks: for cancer-related chest wall pain, metastatic rib involvement.
• Neurolytic procedures: using alcohol or phenol, they create a longer-lasting nerve lesion, indicated in patients with limited life expectancy and refractory pain.
• Vertebroplasty and kyphoplasty: for vertebral metastases with pain from vertebral collapse.
• Percutaneous cordotomy: for patients with refractory unilateral cancer pain, especially in the chest/upper abdomen, in patients with short life expectancy.
• Intrathecal systems: implantable pumps or catheters that deliver medication near the spinal cord, for patients whose pain is refractory to systemic management.

The choice of procedure depends on the type of pain, its location, the cancer prognosis and the patient's overall condition. An interdisciplinary evaluation is key.

Integrated palliative care

Palliative care does not mean "there is nothing more we can do." It is a branch of medicine focused on relieving suffering and improving quality of life in patients with serious illnesses — ideally integrated early into cancer treatment, not only in terminal stages.

A good palliative approach to cancer pain combines:

• Pharmacological treatment optimized and adjusted to the patient's situation.
• Interventional procedures when they add benefit.
• Management of associated symptoms: nausea, opioid-induced constipation, anxiety, depression, insomnia, loss of appetite, shortness of breath.
• Support for the patient and the family.
• Coordination with the oncology team so that pain-treatment decisions stay consistent with the overall goals of care.

The evidence is compelling: early integration of palliative care improves quality of life, reduces suffering and, in some cases, even prolongs survival.

My approach to cancer pain is to work as a team, always. With the treating oncologist, with palliative care, with physical therapy, with psychology, with the family. I combine carefully adjusted medication regimens with interventional procedures when they add something concrete: celiac plexus blocks in upper abdominal cancer, hypogastric blocks, selective neurolytic procedures, intrathecal infusion systems in selected cases. The goal is not to 'tolerate' the pain, but to truly control it so the patient can live their time as well as possible.

Patients in active treatment and survivors

Two situations deserve particular attention:

Patients in active cancer treatment: they may have pain from the disease and, at the same time, pain caused by the treatment (mucositis, chemotherapy-induced neuropathy, recent post-surgical pain). The plan has to be dynamic, adapting to each phase of treatment. Good pain control improves tolerance to the oncology regimen and reduces the interruptions or dose adjustments that compromise outcomes.

Cancer survivors: their numbers keep growing, and many are left with chronic pain as an after-effect. Survivor pain requires a shift in focus: there is no longer active disease to treat, but there are after-effects (chemotherapy-induced neuropathy, post-mastectomy pain, post-radiation fibrosis) that have specific treatments. Having put cancer behind you does not mean resigning yourself to living with pain.

What defines success in cancer pain, for me, is very concrete: a patient who sleeps, who eats, who can be with their family, who keeps their independence for as long as the disease allows. That is only achieved when the pain is properly treated, without unfounded fears and with a comprehensive strategy. Walking alongside these patients and their families is one of the most demanding — and at the same time most meaningful — parts of pain medicine. Doing it with time, with listening and with knowledge is a responsibility that goes far beyond prescribing a painkiller.

Dr. Mauricio Casarsa

Anesthesiologist, specialist in Pain Medicine and Interventional Pain Management. Postgraduate training at UBA (Fundación Dolor) and UNLP (CAIDBA). Staff physician at Hospital Alemán, Buenos Aires.

MN 137756 · San Isidro · Villa Urquiza