This actually is a thought provoking article. I am still reading it, so cannot speak of the merits fully.

For example this para is worth pondering : It is now becoming clear

that natural selection enhances barriers to cancer in proportion

to the organisms need for these barriers – large,

long-lived organisms have evolved enhanced anticancer

adaptations relative to small, short-lived organisms (Seluanov

et al. 2008; Caulin and Maley 2011; DeGregori 2011)."

A cursory search of the animal kingdom shows many animals that live beyond 200 years. How do the cells here survive mutations for that long, but we humans are stuck at 80 years? Or are we just looking at animals within a species that are the exceptions and the rare ones that survive that long? Clams are known that are 500 years old.

Cancer is a good example of a 'stochastic disease'. Among the millions of cells and mutations that are repaired or deleted, there is no perfect system and some errors will always escape. There is no 'intelligent' design but just the laws of probability. The question is whether we humans have evolved LONG enough that the mechanisms are gotten so perfected that probabilities of mutational escape are vanishingly small. Over that, what are we doing to ourselves that we affect how the 'machine' is perfected by selection??? So many questions, before we even get to a 'causative' theory???

Clearly, a stochastic view, implies any disturbance of the balance changes probabilities. Throw in infections and you cannot rule that out, can you?

But this much I will say, given all the information we have amassed on cancer we sadly know the least about it, except be 'fascinated' by it !

Hi,

I copied few links related to this topic. Numerous agents might be responsible for cancer development, the proportion of infected individuals who will eventually develop cancer is low, but the high incidence makes it to a significant number of cases.

Some of these discoveries were recognised as very important on the field of medicine and Nobel prizes were rewarded.

I hope this will bring answers to your questions.

Best wishes,

Karoly

http://en.wikipedia.org/wiki/Infectious_causes_of_cancer

http://en.wikipedia.org/wiki/Helicobacter_pylori

http://www.nobelprize.org/nobel_prizes/medicine/laureates/2005/press.html

http://en.wikipedia.org/wiki/Human_papillomavirus

http://www.nobelprize.org/nobel_prizes/medicine/laureates/2008/press.html

http://en.wikipedia.org/wiki/Epstein%E2%80%93Barr_virus_infection

Hi Szuhai,

thank you for the links. My main problem with the theory, as you mentioned above, is that cancer is caused by many factors; infectious is not the main cause.

Hi,

It may depend on the angle you take.

For HBV endemic regions HCC is really frequent and linked to the infection. As for cervical cancer, it is well accepted fact that almost all cases have HPV integrated.Obviously secondary changes, conditions are needed, but for that particular group it is close to 100%. Schistosomia and baldder cancer, in endemic areas are high. (HBV, schistosomia, EBV, HPV in edemic areas are making a great number.) If one took the hit-and-run hypothesis into consideration, the number could be higher, without real evidnece though. Numbers of initiating steps could be caused by sustained inflammation and or dysregulated genetic background permitting novel changes towards a trasnformed state with self sustained proliferation and losing the infections agent during development.

I think you really need to go with facts on certain types of cancers with proof, and of course should not leave the others out.

Best,

Karoly

I think you should read "Valganciclovir in Patients with Glioblastoma" in Nejm.

It might be useful for you. Greets.

Dear Michael,

The case of Burkitt's Lymphoma is a good example. Cervical Cancer is another good example.

There are more examples of infectious causes of tumorigenesis in people and animals, including hairy call leukemia and Kaposi's sarcoma in HIV infected humans, acutely and chronically transforming retroviruses causing lymphomas and leukemias in various animal and avian species, H. pylori, gastric cancer in man , Spirocerca lupi induced fibroma or fibrosarcoma in dog oesophagus, and more commonly Cysticercus fasciolaris indued fibrosacoma in rat liver and several more. All these infectious agents except viruses cause chronic inflammation and dysregulation of immune response, resulting eventually in cancer. But still more is unknown about cause and effect relation of infectious agents and cancer.

This actually is a thought provoking article. I am still reading it, so cannot speak of the merits fully.

For example this para is worth pondering : It is now becoming clear

that natural selection enhances barriers to cancer in proportion

to the organisms need for these barriers – large,

long-lived organisms have evolved enhanced anticancer

adaptations relative to small, short-lived organisms (Seluanov

et al. 2008; Caulin and Maley 2011; DeGregori 2011)."

A cursory search of the animal kingdom shows many animals that live beyond 200 years. How do the cells here survive mutations for that long, but we humans are stuck at 80 years? Or are we just looking at animals within a species that are the exceptions and the rare ones that survive that long? Clams are known that are 500 years old.

Cancer is a good example of a 'stochastic disease'. Among the millions of cells and mutations that are repaired or deleted, there is no perfect system and some errors will always escape. There is no 'intelligent' design but just the laws of probability. The question is whether we humans have evolved LONG enough that the mechanisms are gotten so perfected that probabilities of mutational escape are vanishingly small. Over that, what are we doing to ourselves that we affect how the 'machine' is perfected by selection??? So many questions, before we even get to a 'causative' theory???

Clearly, a stochastic view, implies any disturbance of the balance changes probabilities. Throw in infections and you cannot rule that out, can you?

But this much I will say, given all the information we have amassed on cancer we sadly know the least about it, except be 'fascinated' by it !

Dear Prem,

I apologize if I will not use appropriate terminology I do not know. But do you think it would be possible to evaluate (in sufficient guidance), the incidence of malignant tumors in humans, declassified the effect of chemical carcinogens and the increase in survival due to the medical intervention that tends to become chronic most diseases, including tumors. I understand that the variables are already many and that many more could be added.

About the question referring to my reply to a similar question:

https://www.researchgate.net/post/Can_cancer_come_from_any_type_of_cell_or_are_there_some_cell_types_that_never_produce_cancer

Cancer certainly is a multifactorial disease affecting the cell cycle, therefore proliferation and apoptosis alterations lead to immortality and malignant phenotype. Having said that, anything producing changes that ultimately affect the cell cycle would be carcinogenic. Carcinogens are roughly classified in 3 kinds: physical, as radiation; chemical, like pesticides an other sort of mutagens, and biologic agents, such as all those infectious agents that you just have mentioned above. So, I think if you discuss that paper, you have the right to disagree in some extent if you think that exposure to chemical and physical agents could reach higher scores as Cáncer causatives rather than infectious diseases. Mainly because in all cancers where infectious diseases are involved, there is a fraction of them where the infectious agent can not be found (demonstrated) as the only or primary cause of that particular cancer. I think the main cause of cancer would be mutation. Best regards!

Virus that can cause cancer is called an oncovirus. These include human papillomavirus (cervical carcinoma), Epstein-Barr virus (B-cell lymphoproliferative disease and nasopharyngeal carcinoma), Kaposi's sarcoma herpesvirus (Kaposi's Sarcoma and primary effusion lymphomas), hepatitis B and hepatitis C viruses (hepatocellular carcinoma), and Human T-cell leukemia virus-1 (T-cell leukemias). In addition to viruses, certain kinds of bacteria can cause some cancers. Bacteria have been linked to cancer by two mechanisms: induction of chronic inflammation and production of carcinogenic bacterial metabolites. The most specific example of the inflammatory mechanism of carcinogenesis is Helicobacter pylori infection. H. pylori have been epidemiologically linked to adenocarcinoma of the distal stomach by its propensity to cause lifelong inflammation.

If speaking of cancer broadly, I've seen estimates of 15% to 20% causation (DM Parkin "The global health burden of infection-associated cancers in the year 2002" (2006) Int. J. Cancer 118, 3030-3044).

The notion of infectious diseases being the primary cause of cancer seems to downplay what is recognised as an enormous contributor - smoking. Smoking remains the most significant (obviously preventable) cause of cancer. Infectious diseases are, however, increasingly being recognised as preventable causes of cancer, especially as vaccination addresses more and more - HPV and Hep B in particular.