Why Glioblastoma remains one of medicine’s most brutal challenges even in the age of immunotherapy and precision oncology

When patients hear the word "glioblastoma", the question that inevitably follows is: “With all the advances in modern medicine, why is this still so hard to treat?”

Good question there. We are in an era of genomic sequencing, immunotherapy, robotic surgery, and artificial intelligence. But the outlook for glioblastoma, the most aggressive primary brain cancer in adults, remains grim. The latest data from the Central Brain Tumour Registry of the United States (CBTRUS) show that median survival for most patients is still only around 15 months despite surgery, radiation and chemotherapy. Fewer than one in ten patients live longer than five years.

As an oncologist, I hear patients and families often express surprise at these numbers. They assume that because medicine has changed the outlook for many cancers, it must have done the same for brain tumours. Regrettably, glioblastoma has been one of the most formidable enemies in the field of oncology.

The answer is in the disease’s extraordinary biology.

Glioblastoma is not like most cancers, which tend to form as relatively uniform masses. It is more like a constantly evolving ecosystem. Different groups of cancer cells in the same tumour may have different genetic mutations and survival strategies.

Research in Nature Reviews Clinical Oncology has shown that within a single glioblastoma there can be multiple genetically diverse cell populations. When a treatment kills one population, another often survives and proliferates. The tumour can evolve faster than we can keep pace with our therapies.

Survival gains have been frustratingly modest nearly 20 years after the seminal work of neuro-oncologist Roger Stupp established surgery followed by radiotherapy and temozolomide as the global standard of care. That’s not to say medicine has stopped innovating, but the disease itself is remarkably adaptable.

The brain is another challenge. Nature constructs the blood-brain barrier, a highly selective protective shield that blocks out harmful substances from entering the central nervous system.

In Nature Reviews Drug Discovery and the journal Neuro-Oncology, researchers have observed multiple times that many of the cancer drugs that could work well struggle to get across this barrier in sufficient amounts. A treatment that works well elsewhere in the body may never reach the tumour hidden in the brain.

Immunotherapy has transformed outcomes in melanoma, lung cancer and a number of other malignancies but so far has had only limited success in glioblastoma. Reviews published in both the New England Journal of Medicine and Nature Reviews show, “Glioblastoma creates an immunosuppressive environment that effectively neutralises a lot of the body’s own anti-cancer defences." The tumour is not just growing. It is defending itself.

These scientific facts also pose profound ethical dilemmas.

When standard therapies provide only limited survival gains, patients and families understandably focus on experimental options. Physicians have to have tough conversations often: Can a patient be ethically asked to participate in a clinical trial with a high risk and uncertain benefit? How do we balance hope and honesty? How do we prevent desperation from becoming exploitation?

Every treatment that ever becomes standard therapy starts as an experiment. But we also have a responsibility to recognise uncertainty and to focus on quality of life as well as survival. Those conversations are often among the most difficult and most important we have in neuro-oncology.

Still, there are reasons for guarded optimism even with the sobering statistics. Advances in molecular profiling are helping clinicians to identify subgroups of patients who may benefit from more personalized approaches. Novel drug delivery systems are being developed to overcome the blood brain barrier. Early-stage studies presented at recent meetings of the American Society of Clinical Oncology (ASCO) have indicated encouraging signals for personalized vaccines, engineered CAR-T cells and other next-generation immune therapies.

These are not cures. But they are significant scientific progress.

The Glioblastoma story is not a story of medical failure. Instead, it is a reminder of the complexity of human biology. Some diseases yield quickly to scientific advance; others challenge us to confront the limits of our knowledge.

It is not that medicine has given up on glioblastoma, but rather that this tumour continues to humble us. The challenge for the next decade is not only to treat it more aggressively but to understand it more deeply. Ultimately, that understanding is where the greatest hope resides.

Dr Anthony Vijay Pais, Clinical Director of Oncology & Head of Oncoplastic Breast Surgery at HOSMAT Hospitals