My mother was a perfectly healthy woman, a non-smoker without any cancer in her family tree. In 2007, I went through a major depression which made her very very sad. She is a very sensitive women, very susceptable to issues dealing with me as I'm her only child. I was telling her everyday that I was feeling suicidal. 2008- she gets cancer. I'm trying avoid the thought that I might be the reason for her cancer but it's always in the back of my mind. I blame myself for it and putting myself into such intense regret. What do you think about stress and cancer?

Whatever the relationship between stress and cancer, my opinion is that there is little if any likelihood that you are the reason for her cancer. Especially in only one year (2007-2008). Such thinking is part and parcel of the confused reasoning of depression. If you would just do the math, you would realize that if worrying about your child caused cancer, virtually every parent would have cancer.
It does not sound to me like you are a parent: I am and have been for over twenty years and trust me when I say that I have worried, worried, worried about my child -but that did not cause my cancer. HPV 16 & my immune system did.
Focus on comforting your mother and being a good caregiver. You are not helping her or yourself with this negative fantasy.
Charm

Preference my remarks with I'm not a doctor or anything close to one but I personally feel that stress can diminish the effectiveness of our immune system and to the extent that a virus may cause cancer then it is conceivable that the virus may be able to do it's damage when possibly it wouldn't have been able to without a stressed mental state.

As far as you wanting to take responsibility for your mom's cancer I believe it's just your guilt looking for closure which to me is a positive sign and I would redirect that by telling her (every day for a while if that's what it takes) that you are sorry for any pain/suffering you may have caused her when you were going through a rough period.

This is what I believe also, constant stress of her daughter feeling suicidal weakened her immune system. I even remember her telling me "this is making me so upset, im gonna get sick". I do tell her that im really sorry as much as I can, but i can't stop crying when i do that. I wish i could take it all back. self loathing is miserable.

As a therapist I work with depression, stress,etc all the time. Do I think stress can affect one's physical health? Yes. Do I think you caused your mom's cancer? NO.
There are people that deal with unbelievable amounts of stress for years and remain healthy. There are people that deal with minimal stress and get sick. And everything in between.

I think cancer does not discriminate and very often it is so hard to make sense of . It affects people of all ages, male, female, all races, ethnic groups,etc. It affects people who have stress and happy go lucky people.

Self loathing is miserable and I feel for you. I very much hope that you are getting help to deal with those feelings. That has to be such a rough way to live.

As a parent,I would never, ever want my kids to feel responsible for my health. I'm guessing your mom feels the same way

Susan, thank you, thank you, thank you. It's really valuable to hear this from a therapist. Getting those negative thoughts for me is inevitable and I know I'll go back to it but your message will have me sleep peacefuly tonight, that's for sure. Do you suggest I should talk with a therapist? I don't know what's in store for me and my mom, she's my best friend. I don't think I can exist without her. I'm so lost sometimes. The fear of losing her combined with the guilt really gets me down. A history of depression doesn't help either. I'm just wondering where my life went, still hard to believe this is not a nightmare I can wake up from. Sometimes I want to feel distant from her so that I don't get irreversably depressed from whatever might happen. But i think at this stage putting an emotional distance would be cruel to her, because she's my mother and she'd feel it. Plus i dont even think i can feel that way. Sorry i'm rambling here...

Well,I have to admit to a bias but...given everything you have going on right now it might be helpful to talk to someone.

It's like having a case of 'racing car" brain,isn't it? All these thoughts just keeping going round and round really fast.
It can be helpful to have someone help you sort it through and/ or help you to slow it down. Sounds like you have a lot going on. Some extra support might really help.

[quote=zeynepuygun] I blame myself for it and putting myself into such intense regret. What do you think about stress and cancer? [/quote]

Please have your mother get her Vitamin D levels tested. Low Vitamin D level is closely tied to breast, prostate and colon cancer. It is linked to all type so cancer as well. My level was 22 before I got cancer. Mid range level is closer to 50. The bottom of the range (30ng/ml) is completely outdated. Insist that you get a copy of the test results rather than a phone call where a nurse says "everything is normal".