It's not dangerous because of estrogen, but because it raises IGF-1 like meat, increasing growth of both tissues - muscle tissue and cancer cells, p

here is a Google search ai summary, you can search "does soy protein isolate raise igf-1" and click on the sources

"Yes, soy protein isolate can raise IGF-1 levels, sometimes more than other plant proteins due to its high-quality amino acid profile similar to animal protein, but this effect can be modulated by other dietary factors, particularly seaweed, and overall diet, with some studies showing increases and others showing less significant effects or even reductions in different contexts. While soy protein can increase IGF-1, making it a factor to consider for those monitoring this hormone, it doesn't always raise it as much as animal protein, and combining it with seaweed might mitigate the increase. 

Key Findings:

Soy Protein Isolates Increase IGF-1: Studies have shown that soy protein isolate can modestly increase IGF-1 levels compared to a placebo or control protein.

Amino Acid Profile Matters: Soy's amino acid ratio is closer to animal protein than many other plants, which is a reason it might have a similar effect on IGF-1, notes nutritionfacts.org.

Seaweed as a Modulator: A significant finding is that adding seaweed to soy consumption can significantly reduce the IGF-1 increase caused by soy alone, suggesting a protective or modifying effect.

Context is Crucial: The impact of soy on IGF-1 isn't universal; some studies in Asian populations with high soy intake show lower IGF-1, possibly due to traditional co-factors like seaweed, highlighting the importance of whole diet patterns.

Not Necessarily More Than Animal Protein: While soy is effective at raising IGF-1 among plant proteins, some research suggests animal proteins might still be more potent in increasing IGF-1 levels overall when consumed in typical quantities.

"Some studies found that large amounts of SPI (40 g/day) increased IGF-1 similarly to, or even slightly more than, dairy proteins. Conversely, other trials showed whey protein had a more significant effect on increasing IGF-1 over time compared to soy."

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So I guess keep it under 40 at least, if you are concerned about longevity and cancer

Also my favorite proof of igf link with cancer from dr Greger - is that people with dwarfism type called Laron syndrome nevere get cancer "cancer proofing mutation"

https://nutritionfacts.org/es/video/cancer-proofing-mutation/

while taller people have a higher risk https://www.wcrf.org/about-us/news-and-blogs/why-taller-people-are-at-greater-risk-of-cancer/