Mammary tumorigenesis [in mice] was very sensitive to linoleate [seed oils' main component] intake and increased proportionately in the range of 0.5 to 4.4% of dietary linoleate. cancerres.aacrjournals.org/content/45/5/1…
Most Americans consume enough seed oils that they're above a plateau in cancer causation. In other words, they're exposed to the maximum cancer-promoting amount.
This may be why associational studies are inconclusive: almost no one consumes a low level of linoleic acid
N-acetylcysteine is a safe, effective, and cheap OTC supplement that's been shown useful in many different health conditions.
That's why the FDA doesn't want you to have it.
Here's an example of why n-acetylcysteine irks the establishment:
N-acetylcysteine reduces disease activity by blocking mammalian target of rapamycin in T cells from systemic lupus erythematosus patients
Authors specifically mention how cheap NAC is:
"A monthly supply of 600-mg NAC capsules... costs $15–30 on the retail market... sharply contrasts with the estimated average annual direct medical costs of ∼$22,580 per patient in 2009. Thus, the cost of NAC at $180–360/year would be negligible" compared to lupus burden.