system
Given the following post, respond as if you're commenting on Reddit:
human
Why is cancer rare in fat cells?
gpt
Short answer: fat cells don't undergo a great deal of cellular turnover and are probably relatively unlikely to acquire cancer-causing mutations compared to most other cell types. However, while malignant fatty tumors (liposarcomas) are very rare, benign fatty tumors (lipomas) are exceedingly common.

Long answer: cancer biology is a huge field that can't easily be painted in broad strokes—there are a wide variety of types of malignancies, each of which is different and has its own unique pattern of development. To oversimplify, though, the propensity for cancer to develop out of a given tissue often involves at least a few common factors:

* **How much trauma or inflammation is the tissue is exposed to, and how does the tissue respond?** The more insults that a cell type is subject to, the more DNA damage the cell accrues, and the harder that cell's DNA repair mechanisms have to work to keep up to prevent cancer-causing mutations. Over time, abnormal and autonomous/excessive cell division (dysplasia and neoplasia, respectively) may occur, laying the groundwork for cancer.
* **How much (and what kind of) hormonal stimulation does the tissue receive?** Certain tissue types, like breast, endocrine, and prostate cancers, are known to be exquisitely sensitive to hormonal feedback—particularly stimulation from hormones that encourage cell growth and division. For example, typical prostate cancer is known to be highly responsive to androgens such as testosterone and DHT, so anti-androgenic drugs (e.g., bicalutamide) form a cornerstone of therapy for advanced prostate cancer.
* **How much cellular turnover does that tissue normally experience?** We often see cancers arising from epithelial cell layers—like those found in the GI tract, parts of the upper respiratory system, and the skin—that turn over or constantly generate new cells (also called labile cell types). These tissues may acquire mutations more easily simply because they are constantly synthesizing new DNA and dividing, which gives their enzymes more opportunities to "make mistakes" in the process. In addition, these cell types are frequently exposed to potential carcinogens in the environment (e.g., UV radiation on the skin or chemical irritation in the GI tract) and thus are subject to more cell damage as above.
* **How do the cells in that tissue interact with each other?** Certain cell types are specialized to associate easily and closely with other cells. This is mainly influenced by the connective proteins and receptors expressed on the cell's surface. Certain types of cells can more easily acquire mutations that cause abnormal surface proteins to be produced, which then facilitate malignant transformation (e.g., the cell can loosen its local attachments, invade into the bloodstream or lymphatics, and metastasize).

While fat cells (adipocytes) do experience a fair amount of stimulation from hormones—notably insulin and other metabolic regulators—they are relatively sheltered from most exogenous carcinogens, don't associate very tightly with each other, and don't undergo much baseline cell division. As a result, mutations that produce true malignancy (i.e., liposarcoma) are rare. On the other hand, benign tumors of adipocytes (lipomas) are very common, so it's possible that small-scale local trauma, endocrine stimulation, and/or other mechanisms may produce neoplastic growth without the development of malignant features (esp. tissue invasion and metastasis).