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Author Topic: Can anyone clarify the situation re cancer?  (Read 1324 times)

Offline pantodragon

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Can anyone clarify the situation re cancer?
« on: 07/02/2013 16:01:11 »
I heard an epidemiologist talking about her work the other day.  She raised the issue of breast cancer, claiming that there was a connection between the rates of cancer and the number of children that women had: women in the developed world who had few children had higher rates of breast cancer than women in the non-developed world who had many children and breast fed them for longer.  She left the subject there, leaving me to wonder if this connection was purely a matter of statistics or has there been a follow up that has found a mechanism to explain why this happens.

Can anybody clarify the current state of research on the subject?


 

Offline RD

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Re: Can anyone clarify the situation re cancer?
« Reply #1 on: 07/02/2013 17:04:35 »
It's the pregnancy , not just the breastfeeding  ...

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Women who have a full-term pregnancy before their mid-20s substantially reduce their lifetime risk of breast cancer, compared with women who either have children later in life or do not have children, according to many epidemiological studies. Women who breast-feed their babies further reduce that risk.
http://jnci.oxfordjournals.org/content/early/2010/04/13/jnci.djq146.full


If you're Googling the key phrase is "protective" ...

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The protective role of pregnancy in breast cancer
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1143568/
 

Offline Bored chemist

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Re: Can anyone clarify the situation re cancer?
« Reply #2 on: 07/02/2013 17:07:07 »
It's also (broadly) consistent with the observation that breast cancer correlates with early menarche and late menopause.
 

Offline evan_au

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Re: Can anyone clarify the situation re cancer?
« Reply #3 on: 09/02/2013 03:32:08 »
It is known that in some women, monthly changes in hormone levels causes proliferation of cells in the breast. http://en.wikipedia.org/wiki/Fibrocystic_breast_changes#Causes

The new cells probably originate from stem cells in the breast. When cells are multiplying at an increased rate, there is an increased chance of copying errors, some of which could later result in cancer.

However, it seems that epigenetic changes with pregnancy and breastfeeding can modify the behaviour of breast tissue.

While there are many genes thought to contribute to breast cancer (most of them with a small impact), some of the well-known genetic variants like BRCA1 & BRCA2 relate to repairing DNA errors, and p53 relates to apoptosis in cells with uncorrectable errors. http://en.wikipedia.org/wiki/Breast_cancer#Genetics

Together, this suggests that there are more cell division cycles in the breast (and thus an increased risk of a dangerous mutation) with:
  • Early menarche
  • Zero or small number of children
  • No or small amount of breastfeeding
  • Late menopause
  • Pre-existing mutations related to DNA repair
  • Exposure to known carcinogens like smoking

As the identification of breast-cancer genes has slowed significantly in recent years, perhaps more information can be obtained with studies of the epigenetics of breast cancer? (Newer DNA sequencing machines are able to report on some epigenetic factors, as well as the genetic factors.)
« Last Edit: 09/02/2013 04:18:02 by evan_au »
 

Offline pantodragon

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Re: Can anyone clarify the situation re cancer?
« Reply #4 on: 11/02/2013 15:48:58 »
Thank you all for your informative comments.
 

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Re: Can anyone clarify the situation re cancer?
« Reply #4 on: 11/02/2013 15:48:58 »

 

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