Anyone know about cancer and genetics?

[eyesroll]

Another family member was diagnosed this morning.

So far, we've got:
1. Maternal uncle, diagnosed with breast cancer in his 50s (survived; prognosis good)
2. Maternal grandmother, breast cancer in her 40s and in her 60s (mastectomy both times); liver cancer in her 70s (did not survive, but declined treatment)
3. Paternal grandmother, breast cancer in her 70s, currently undergoing treatment, prognosis excellent
4. Paternal grandfather, thyroid cancer in his 70s, had his thyroid removed, no trace of the cancer, prognosis excellent
5. Paternal aunt, breast cancer in her 40s; died about 5 years after diagnosis
6. Paternal uncle, 43, leukemia; diagnosed this morning so prognosis unknown to me at this point.

My dad, thus far, has been cancer-free; my mom has had polyps removed during colonoscopy and pre-cancerous cervical lesions removed but that's about it. No actual cancer in my immediate family.

They all originate from Chicago (city and suburbs), but they live in different parts of the country. No high-risk occupations or power lines or anything.

I know there are genetic markers for breast and ovarian cancer, but what about cancer in general? This is getting spooky, and depressing...

Edited to correct a typo...and to add that perhaps one common factor is that they're all upper-middle-class to affluent, and are in a demographic likely to have lawn services and dry cleaning more frequently (and I have read about anecdotal links between cancer and those kinds of chemicals -- but it is just anecdotal).

[commander bunnypants]

1. A little bit- Also I am not an MD

Cancer cells attack healthy cells and by changing their chromosomes make new cancer cells. There is also environmental factors, race, sex factors. If you care to PM me and I can research a question if you need

DEMMAN

[Snow]

2. A little bit as well....

and while not an MD I am a PhD epidemiologist (hence the moniker). Coupla things to understand here:
- all diseases have multiple causes. Sometimes geneticists like to act like a given gene is <U>the</U> cause, but that's almost never the case, especially with cancer.
- a lot of things can look like genetics but are actually shared environment. A real good example was pellagra amongst blacks in the american south. A lot of Koreans, where I was in the Peace Corps, thought tuberculosis was genetic because it often clustered in families.
- when you have a nasty scary disease strike someone close to you, you start really looking around to se who else in your circle might have the same problem. Thus you count cases that might not have otherwise been noticed. There's a good example of that in a cancer cluster in recent (okay, 10 years ago is recent when you're my age) graduate of an Iowa high school to whom I consult. They're doing a great job of finding cancer cases but not so great a job of locating the denominator - that is, what's the group of people from whence those cancer cases came. The same question applies in your case....how big is your family - I notice you're counting both parent's families...and from that, how many cases of cancer would be expected in a group of that size. And if it proves to indeed be more than expected, it could still be a random occuurence of a cluster - those do happen.
- Finally, cancer is not a homogeneous disease; it's a collection of very different diseases with enormous variety in the causes. The leukemia and the thyroid cancer, for example, arise from very different causes. And the breast cancer, we frankly don't understand at all.
Be careful of trying to look for any one cause, though - such a thing almost never exists. Even with lung cancer and smoking, plenty of people smoke but never get lung cancer. Live in a healthy fashion, exercise, eat your veggies, don't smoke, and you'll be doing pretty well. Get regular check-ups, too - but don't get to freaked out by this all.

[Snow]

3. A little bit as well....

and while not an MD I am a PhD epidemiologist (hence the moniker). Coupla things to understand here:
- all diseases have multiple causes. Sometimes geneticists like to act like a given gene is <U>the</U> cause, but that's almost never the case, especially with cancer.
- a lot of things can look like genetics but are actually shared environment. A real good example was pellagra amongst blacks in the american south. A lot of Koreans, where I was in the Peace Corps, thought tuberculosis was genetic because it often clustered in families.
- when you have a nasty scary disease strike someone close to you, you start really looking around to se who else in your circle might have the same problem. Thus you count cases that might not have otherwise been noticed. There's a good example of that in a cancer cluster in recent (okay, 10 years ago is recent when you're my age) graduate of an Iowa high school to whom I consult. They're doing a great job of finding cancer cases but not so great a job of locating the denominator - that is, what's the group of people from whence those cancer cases came. The same question applies in your case....how big is your family - I notice you're counting both parent's families...and from that, how many cases of cancer would be expected in a group of that size. And if it proves to indeed be more than expected, it could still be a random occuurence of a cluster - those do happen.
- Finally, cancer is not a homogeneous disease; it's a collection of very different diseases with enormous variety in the causes. The leukemia and the thyroid cancer, for example, arise from very different causes. And the breast cancer, we frankly don't understand at all.
Be careful of trying to look for any one cause, though - such a thing almost never exists. Even with lung cancer and smoking, plenty of people smoke but never get lung cancer. Live in a healthy fashion, exercise, eat your veggies, don't smoke, and you'll be doing pretty well. Get regular check-ups, too - but don't get too freaked out by this all.

[Nikia]

4. I remember a little bit from moleculear biology

We read and discussed a paper about it. The basic summary of it was that some genes make cancer (excessive immortal cell growth) more likely and some genes will kill these cells. There are a few that do each. Ideally, you will have no genes that will spontaneous prodcue immortal cells and have genes to kill immortal cells if they would occurr through environmental mutation. Most people have a mixture. My family is relatively cancer free and thus my grandfather claims he has nothing to worry about as he continuously smokes all day. The good thing is that if cancer is caught early, it can be removed. I am not saying that you should be paranoid, but you may want to be concious of the signs of it. I am even though I do not have direct ascendents or family members in my parent's generation with cancer.

[Lexingtonian]

5. Sounds intriguing

It's hard to draw a firm conclusion from what you tell- you don't mention the total number of related people involved, the ones whose cause of death was other things, or ethnicity- but I think it's possible to exclude some things.

Where there are strong carcinogens in the general environment it shows up as childhood cancers, usually leukemias. When it's clearly genetic it tends to run in one side of the family rather than both and strike young.

There isn't a way of entirely excluding either one, but they don't fit those patterns in my opinion (unless your ancestry comes to a large extent from the Jewish Pale, which greatly complicates things). It may also be that what is seen in your family has two or three distinct causes.

But what you tell does so far fit as a pattern is what you might call 'cultural' causes- that's factors usually linked to long term habits such as diet or smoking or other cultural group practices. In the U.S. it tends to account for over 80% of all cancers, and amounts to long term and persistent exposure to weak carcinogens. Among average white Americans the culprits tend to usually be smoking, nitrate-treated cured meat, burnt meats, and ashes digested via food. Particulates from incomplete combustion are also significant in some areas (e.g. southern Los Angeles), PCBs and stuff like tannery leachate matter in drinking water. (Non-blood cancers seem to generally be accelerated, but not caused, by a high fat diet. Pesticides and insecticides seem to have far more significant neurological effects than carcinogenic ones.)

The good news is that present generations are exposed to far less of all these dietary and microenvironmental carcinogens than older ones except the fat. The bad news is that it is nonetheless cumulative, and you may now be seeing as cancer the effects of lifestyles of the '40s, '50s, and '60s.

I am not a doctor but work in associated biological research with cancer as a side interest.

For our interested other readers, I didn't have the heart delete this part which wasn't completely relevant:

Steroid hormone involvement in womens' cancers is a complicated story, but it seems to point back to two simple things- at relatively fatty diets or obesity as accelerators (e.g. Japanese women) and historically unusual amounts of completed menstrual cycles (e.g. American lesbians) as quasi-causal. As I understand the literature, use of the Pill is helpful before menopause and estrogen replacement therapy ambiguous or slightly unhelpful in that regard. But female reproduction is turning out to be even more poorly understood as a system than doctors and biologists thought, so everything in that realm is in some amount of haze at the moment. They've just figured out that ovulation and menses are not coupled 1:1, so 22 year old women may have three or four ova released in a month and 45 year old ones probably less than one. What few things they understand about mammary glands beyond the obvious is even more pathetic- the biology basis for understanding of breast cancer even at a gross cellular level is grotesquely close to nonexistent.

[Snow]

6. Yes, we get hung up on old hypotheses

and next thing you know, we think that's the way of the world. Because we thought of breast cancer as a disease of the breast (rather than a systemic disease) we thought it must be related to female hormones - and the whole story of breast cancer research to the present day is a largely unsuccessful attempt to figure out which female hormones play what kind of role in breast cancer etiology, including all ths stuff about diet and exercise. We also walked down that road with cervical cancer, before we got knocked over the head with the papilloma virus being a huge part of the causation - but that took some real re-organization of our thinking. It happened after Burkitt discovered his lymphoma in Africa caused (in part) by an epstein-barr virus, and a little after the appearance of the AIDS epidemic, with its accompanying Kaposi's sarcoma. Up till that time, the late 70's early 80's, we thought cancer and infectious diseases were separate realms. Still do, to some degree.....