The human body is made up more than a hundred million, million cells. These building blocks of life exist in a state of constant change, with new cells replacing old cells in a steady, continual process. But when that process goes terribly awry, cancer occurs. We are accustomed to cancer happening in the human body, but in the new science fiction thriller Annihilation, cancer is the premise of something far more sinister.

Major spoilers below for Annihilation.

The film is rife with references to cancer. Near the start of the film, Lena (Natalie Portman), a cell and cancer pathology expert at Johns Hopkins University, shows slides of cells dividing and mutating. These cells, she reveals, belonged to a woman with ovarian cancer. Later, before entering Area X together — the alien-like environment that is their mission to explore — Jennifer Jason Leigh’s Dr. Ventress confides to Lena that she is dying of the disease.

Once they get to Area X, however, cancer appears to affect life beyond humans and animals.

Jennifer Jason Leigh in "Annihilation."

The team of female scientists start seeing strange creatures, like crocodiles with shark teeth and exotic flowering plants with bizarre forms that appear to originate from the same plant. Lena describes the anomalies as “malignant,” a term often used to describe cancerous tumors that can divide uncontrollably and spread cancer to other cells in the body.

When the scientists encounter plants with human-like shapes, we learn that in Area X, the genetic code of living beings becomes distorted on a subcellular level, leading to creatures like the crocodile with shark teeth. Then, when Lena examines her blood under a microscope, she sees that her own cells are dividing in a decidedly abnormal way.

In the book, but not the movie, Lena's husband dies from cancer.

There are unrestrained, biological changes happening in Area X, with each affected organism becoming more powerful with every mutation. It doesn’t perfectly mirror what happens to a body infected with cancer, but the disease’s quintessential characteristic — mutation leading to unchecked growth, movement, and power — are the same.

In addition to observing this in the strange creatures of Area X, we see it also with the duplicate of Lena’s husband: Kane, the human, falls to madness and dies within Area X, while his duplicate survives and emerges at Lena’s home. Like a cancer, he spreads beyond his origin within the Shimmer’s border, just as the actual border is spreading.

Cell division
The process of cell division. 

In real life, cancer’s ability to accelerate cell division and growth rates is caused by genetic mutations that give cancer cells a growth advantage. According to the Cancer Genome Project, cancer cells typically have 60 mutations or more. Cancer cells divide more rapidly than other cells, eventually developing into a tumor. The divided copies of that cell ultimately outperform noncancerous cells for resources, leading to further disease.

Unfortunately, cancer in the real world can’t be blamed on something as simple as Area X. It has many causes, like inherited mutations or exposure to exogenous substances like tobacco smoke and ultraviolet rays. Perhaps most terrifyingly, cancer can also be a result of random chance, as the American Cancer Society notes: “Other mutations have no clear cause, and seem to occur randomly as the cells divide … The number of gene mutations build up over time, which is why we have a higher risk of cancer as we get older.”

Not all gene mutations result in cancer, but if a cell doesn’t detect and repair mutations to its DNA, they certainly can. Once a cell becomes cancerous, it can evade programmed cell death, making it easier for it to rapidly divide and spread throughout the body.

Area X, like cancer, seems to upset the natural balance that keeps biological processes in check. But unlike cancer, it’s ultimately unclear whether the changes that occur in Annihilation are good or bad. Ventress, who likely sees her cancer reflected in Area X, examines the terrain and declares that “it’s destroying everything.” Lena disagrees: “It’s not destroying, it’s making something new.” Either way, it’s clear their world can’t be diagnosed as benign.

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