Doc Talk

New hope for rare pancreatic cancer

Many new drugs and new therapy have emerged to treat Pnets

Pancreatic neuroendocrine tumours, or Pnets, came under the spotlight after the late Apple co-founder, Steve Jobs, was diagnosed with the condition.

Before that, not many people knew about them. Unlike the common type of pancreatic cancer known as adenocarcinoma, Pnets are rare. They account for less than 3 per cent of all pancreatic tumours.

Due to their rarity and the paucity of reliable medical evidence in the treatment, managing patients with this condition can be very challenging. Specialists have to rely on their clinical experience and judgment.

It does not help that Pnets may not have signs or symptoms. This means the cancer could be diagnosed late, at which point surgery may no longer be an option.

Pnets are also complex. They can appear in various guises and differ greatly in the speed of growth. They can switch gear from slow to fast or from fast to slow.


ST ILLUSTRATION: MIEL

This is why some patients may live for years, even after the tumour has spread to the liver or other parts of the body. Others may not, if their slow-growing Pnets suddenly turn aggressive.

This observation, known medically as the flip-flop phenomenon, describes the unpredictability and interchangeability of cancer biology.

Predicting the growth velocity of these tumours remains an inexact science at best.

It brings to mind a patient, Mr P, who was diagnosed with metastatic Pnets, which had spread to his liver when he was in his 40s.

He had a moderate-grade tumour and underwent major pancreas and liver surgery to remove as much of it as possible.

Surgery is not a straightforward medical decision. It is generally not recommended if the cancer has spread.

It was not surprising that Mr P had received mixed opinions from other oncologists and surgeons.

From cumulative experience worldwide, we know that extensive surgery can prolong the survival of patients, provided it can be performed safely.

It was a tough decision for Mr P. The surgery was risky and he was not sure if it would be a success. If he opted for it, he would have to live with a high risk of tumour recurrence. It was only after much deliberation with his family members that he decided to proceed with it.

Fortunately, the surgery was a success and almost all the visible tumours in the pancreas and liver were removed.

Singapore has had the foresight to invest in the therapy (peptide radionuclide receptor therapy), as well as the training of related professionals. This means that patients who need it - those who have not responded to other treatments for Pnets - can now get PRRT locally.

However, about a year later, new tumours returned in his liver. To treat the small tumours, he opted for hormonal therapy using a somatostatin analogue. This mimics the body's natural hormone somatostatin and blocks its activity.

The treatment can lessen the symptoms caused by excessive hormones released from the tumour cells, as well as control the growth of Pnets.

Mr P first used a hormone drug called octreotide. When another somatostatin analogue, called lanreotide (Somatuline), was approved for Pnets, he switched to it.

It does not require preparation and the patient can self-administer it once a month. He simply injects it into the fat tissue under the skin.

Studies have shown that the use of Somatuline in the treatment of advanced Pnets reduced the chance of the tumour growing again by half, when compared with a placebo treatment.

Mr P has been on it for more than a year and, so far, it has proved effective in shrinking his tumours and keeping the growth in check.

He has managed to maintain his quality of life, even though it has been more than three years since his major operation.

Apart from lanreotide, many new drugs and new therapy, from molecular medicine and hormonal therapy to targeted therapy, have emerged to treat Pnets in recent years.

One new therapy is peptide radionuclide receptor therapy (PRRT), which involves the administering of a radioactive protein that can target and kill cancer cells.

Phase III clinical data, which is required for regulatory approval, will be available only a few years later.

However, Singapore has had the foresight to invest in the therapy as well as the training of related professionals. This means that patients who need it - those who have not responded to other treatments for Pnets - can now get PRRT locally.

Before 2013, patients here had to travel overseas for the therapy.

Hopefully, newer agents in immunotherapy will also have a definitive role in the treatment of Pnets in the near future.

But the jury is still out on whether surgery should apply to all advanced Pnets cases.

Sometimes, despite the option of a technically feasible and safe operation, surgery is not recommended, especially when we know that the chances of prolonging life are slim.

Using drugs to tame the tumour may be a better option.

New drugs, innovative drug formulation and novel medical technology mean better responses, fewer side effects and better treatment outcomes for Pnets patients.

While waiting for more medical evidence to guide treatment options for this rare cancer, the medical team must put their heads, hearts and hands together to deliver the best outcome possible for each patient.

Dr Liau is a specialist in treating digestive cancers at Nexus Surgical Associates, Parkway Medical Group.

A version of this article appeared in the print edition of The Straits Times on November 08, 2016, with the headline 'New hope for rare pancreatic cancer'. Print Edition | Subscribe