It probably takes years before a tumor grows big enough for normal methods to detect it.
There exist fast-growing cancers. I figure that if the fungi theory is correct, then probably a good amount of this is caused by the specific fungus (and perhaps what part of the body that fungus targets), and most of the rest comes from the target’s immune system (not sure what else would contribute significantly). If transmission and mild infections are common, and if, say, 1% of cancers are fast-growing, I feel like there should be lots of cases where an immunocompromised person picks up a fast-growing cancer fungus at a hospital or something and, within a few years, gets diagnosable cancer. Enough that it should have been noticed. I don’t have numbers for this, but that’s my suspicion.
Or, for example… How often do couples get the same type of cancer? I found this:
METHODS
The authors identified 25,670 cancer-free married couples in northern California who were followed for up to 31 years for the development of cancer. In Cox proportional hazards analysis, the development of cancer in a spouse was treated as a time-dependent, independent variable, and spouse-with/spouse-without risk ratios were determined, controlling for age and gender. For selected concordant espoused pairs, additional explanatory information was sought in their medical records.
RESULTS
There was no excess concordance for all cancers combined; the spouse-with/spouse-without risk ratio was 0.97 (95% confidence interval, 0.90–1.05). Statistically significant husband-wife associations were found only for cancer of the tongue and stomach and for non-Hodgkin lymphoma. Except for cancer of the penis/endometrium and testis/vulva, based on one couple with each combination, gender specific cancers did not aggregate within married couples. Established and suspected risk factors, not necessarily related to the marriage, were found for some individuals who had concordance with their spouses.
CONCLUSIONS
Little spousal concordance for cancer occurrence was found. The study of spousal aggregation does not appear useful in identifying unsuspected environmental causes of cancer in heterogeneous populations in urban areas of affluent Western countries. A cohort study would have to be much larger than this one to detect weak spousal concordance reliably..
Also, for whatever Claude’s opinion is worth:
Q: How often do couples get the same type of cancer?
While it’s not extremely common for couples to get the same type of cancer, it does happen occasionally. This phenomenon has been studied, and there are several factors to consider:
Shared environmental factors: Couples often share the same living environment, diet, and lifestyle habits, which can expose them to similar cancer risk factors.
Similar behaviors: Shared behaviors like smoking, alcohol consumption, or sun exposure can increase risk for certain cancers in both partners.
Infectious agents: Some cancers are caused by infectious agents (like HPV for cervical cancer), which can be transmitted between partners.
Age-related risks: As couples age together, they may face similar age-related cancer risks.
Genetic factors: While not directly shared between couples, people might choose partners with similar genetic backgrounds, potentially influencing cancer risk.
Coincidence: Given the prevalence of cancer, some couples will develop the same cancer by chance.
Screening effect: When one partner is diagnosed, the other may be more likely to get screened, potentially leading to a diagnosis of a cancer that might have otherwise gone undetected.
Studies on this topic have shown:
A slight increase in cancer risk for partners of cancer patients, but this varies by cancer type.
Higher correlations for smoking-related cancers, suggesting shared lifestyle factors play a role.
Increased risk for cancers with infectious causes, like stomach cancer (H. pylori) or liver cancer (hepatitis viruses).
It’s important to note that while interesting, these occurrences are not common enough to be considered a significant public health concern.
There exist fast-growing cancers. I figure that if the fungi theory is correct, then probably a good amount of this is caused by the specific fungus (and perhaps what part of the body that fungus targets), and most of the rest comes from the target’s immune system (not sure what else would contribute significantly). If transmission and mild infections are common, and if, say, 1% of cancers are fast-growing, I feel like there should be lots of cases where an immunocompromised person picks up a fast-growing cancer fungus at a hospital or something and, within a few years, gets diagnosable cancer. Enough that it should have been noticed. I don’t have numbers for this, but that’s my suspicion.
Or, for example… How often do couples get the same type of cancer? I found this:
Also, for whatever Claude’s opinion is worth:
My guess is that almost nobody looks for this kind of connection.
Even if they do notice it, they likely conclude that pathogens are just another small influence on cancer risk.