Why is cancer so hard to fight?

An undead city besieged, where soldiers and police ruthlessly gun down hordes of zombies flooding the infected streets, desperate to escape and infect more cities. This is the thrilling tale that unfolds when your body wages war against cancer, more captivating than any movie. So, how does this epic battle for survival unfold?

The Elimination Phase

It all starts with a single corrupted cell. Unable to repair its damaged genetic code, it loses the ability to self-destruct and begins multiplying rapidly. At this stage, things are not great but not terrible either. This cell isn't yet dangerous, but it soon will be if left unchecked.

Over several weeks, the corrupted cell keeps replicating itself. One cell becomes dozens, then hundreds, and eventually thousands. Since the original cell was already flawed, its copies continue breaking and mutating further. These mutated cells form different genetic lineages, clans that work together while competing. Some mutations weaken them, others have no effect, and a few become more adept at survival. Together, they form a minuscule tumor, not yet classified as cancer, but on its way there.

The growing tumor demands abundant resources. Without sufficient food and oxygen, the cells would die, solving the problem naturally. Unfortunately, a few corrupted cells acquire a new mutation that saves them: the ability to stimulate the growth of new blood vessels. Your body unwittingly supplies the tumor with the nourishment it needs to survive. However, as the tumor continues to expand, it starts causing damage. Healthy neighboring cells starve and perish, attracting attention. In a way, this tiny tumor resembles a rogue town.

Imagine a group of rebels in Brooklyn declaring independence from New York and establishing a new settlement named Tumor Town in the same location. The new city aims to grow, ordering tons of construction materials like steel beams, cement, and drywall. New buildings are constructed without rhyme or reason, poorly planned, ugly, and structurally unsound. They occupy streets, playgrounds, and existing infrastructure. The old neighborhood is demolished or overwhelmed to make space for new structures, leaving former residents trapped and starving. This chaos continues until the stench of death catches notice, prompting the arrival of building inspectors and police.

In your body, the immune system is activated by the scent of dying cells. First-responder immune cells, such as macrophages and natural killer cells, invade the tumor, functioning as the police force. They begin killing and consuming tumor cells while releasing chemical signals to alert the entire immune system of the presence of cancer. Dendritic cells, the intelligence officers of your immune system, collect samples of dead tumor cells and activate specialized weapons: helper and killer T cells. These T cells possess an extensive library of identified threats within your body. Though each cancer is unique, there are genetic abnormalities they cannot conceal. Your T cells are the most effective assassins of cancer.

By the time they arrive, the tumor has grown to hundreds of thousands of cells, but its fate is about to change. T cells impede the growth of new blood vessels, starving thousands of tumor cells and halting their expansion. Picture building inspectors cutting off electricity and water supply, and establishing roadblocks to Tumor Town to prevent further deliveries. With no way to evade the unfolding carnage, the tumor collapses as hundreds of thousands of its cells are mercilessly slaughtered. Macrophages clean up the carcasses, prompting healthy tissue to regenerate. Your body has crushed the illicit Tumor Town without mercy.

You remain oblivious to this battle and the countless times it has transpired within your body. However, in this case, something unexpected occurs.

The Equilibrium Phase

Unfortunately, natural selection thwarts your victory. While diligently aiming to destroy the tumor, your immune system inadvertently favors the fittest tumor cells. Remember, the tumor consists of different lineages that continue growing and mutating. Most of them are eradicated, but a few prove more resilient. One cell survives, belonging to the fittest lineage and exhibiting slightly superior survival capabilities than the rest. It chooses to initiate the cycle once again, but this time, it aims to improve upon its past attempts.

This surviving tumor cell possesses far greater strength than any of the thousands that were slain. It might be better at evading detection or fighting back. Perhaps it grows more rapidly or is more adept at siphoning resources. It could survive with limited oxygen. And so, the cycle begins anew. It's akin to the surviving rebels of Tumor Town learning from their past mistakes, gaining a better understanding of the law, permits that aid them, and methods to evade the police. Consequently, the surviving tumor cell generates thousands of copies that mutate and give rise to new lineages, leading to the growth of yet another tumor. Nevertheless, the immune system remains relentless, and this time, it possesses prior experience. Swat teams composed of T cells directly assault and dismantle Tumor Town, exterminating its inhabitants without mercy.

However, they fail to eliminate everyone once again. One cell manages to survive—a fitter tumor cell from an already fitter lineage. This time, it disguises itself in a cheap suit and studies building codes, pretending to be a lawyer, thereby reigniting the creation of Tumor Town. This struggle repeats itself several times, with the rebels learning progressively more about evading the law. If, at any point, the immune system manages to eradicate all tumor cells, the story ends. But, unfortunately, in this scenario, it does not.

Finally, a tumor cell undergoes a mutation that renders it genuinely dangerous—a cancer cell capable of taking lives. How? Immune cells possess an off switch that deactivates them before they can attack—an inherently good mechanism. After all, the immune system can be incredibly potent and often requires inhibition, particularly around the central nervous system. However, this off switch can be exploited. The mutated tumor cell discovers a method to disable the immune system by targeting inhibitor receptors on anti-cancer cells. These receptors prevent immune cells from fulfilling their lethal function.

This cell becomes the powerful progenitor of a new lineage of cancer cells, rapidly producing thousands of copies that further mutate and diversify. Once again, it constructs yet another Tumor Town.

The Escape Phase

The new cancer cells have become resistant to the immune system, leading to a complete shift in dynamics. Tumor Town is rebuilt, even more grotesque and bizarre than before. This time, the cancer city council fabricates various permits. As building inspectors arrive to halt construction, they become bewildered and disoriented. They fail to issue orders for the destruction of the sprawling structures.

The police attempt to enter the illegal city, apprehending builders and executing inhabitants. However, Tumor Town has established its own roadblocks, preventing law enforcement from entering. Perplexed officers stand idly by, unable to enforce justice. As Tumor Town gradually engulfs the former Brooklyn, and the death toll of civilians rises, SWAT teams of T cells arrive to end this atrocity. Unfortunately, matters deteriorate further. New lineages of Tumor Town officials have begun forging court documents, instructing the police to open fire on the SWAT teams.

At this stage, cancer cells actively suppress immune defenses by emitting corrupt signals. The now malignant tumor no longer succumbs easily and creates the Cancer Microenvironment, a borderland that is challenging to breach. All avenues of attack have been sealed off, and uncontrolled growth ensues. This is a perilous tumor. Strong cells effectively fend off your immune system, pushing it back and expanding further. If additional mutations occur, some cancer cells will venture into other tissues, constructing new settlements.

This is precisely what makes cancer so devastating—it occupies space and deprives your true self of vital nutrients, hindering your normal bodily functions. If allowed to persist for too long, organ failure becomes inevitable. However, this tactic is a dead end. The more successful cancer becomes, the more damage it inflicts upon its own habitat. When the body perishes, so does cancer. Truly, it is a game without winners.

Except humanity is determined to win this game. Currently, hundreds of thousands of scientists are diligently working on new and improved methods to exterminate cancer, to permanently destroy and eradicate Tumor Towns. In recent years, immunotherapy has made significant strides—a relatively new treatment that modifies your immune cells to better combat cancer compared to any medication. It's akin to arming your building inspectors with machine guns and flamethrowers. But that's a story for another time. For now, cancer remains a battlefield. However, if human ingenuity is to be trusted, one day, perhaps in the near future, we will triumphantly eliminate it once and for all.