Genetics, Lifestyle, and Environment

Jacquez et al. (2015) propose a model for understanding the etiologies of cancers based on the interaction of three determinants of illness and health: the Genome (an individual’s biology), the Exposome (an individual’s exposures over the life course), and the Behavome (an individual’s health behaviors over the life course).

The National Cancer Institute (NCI) provides information on Risk Factors for Cancer. “Cancer risk factors include exposure to chemicals or other substances, as well as certain behaviors. They also include things people cannot control, like age and family history.” NCI then lists the “most studied known or suspected risk factors for cancer” (in alphabetical order) — alcohol, cancer-causing substances, chronic inflammation, diet, hormones, immunosuppression, infectious agents, obesity, radiation, sunlight, and tobacco.

In NCI’s The Genetics of Cancer, we are informed that “inherited genetic mutations play a major role in about 5 to 10 percent of all cancers” (par 8). NCI also provides information about Familial Cancer Susceptibility Syndromes and provides guidance as to when a person that has a personal or family history of cancer might want to consider genetic testing to learn whether they might have an inherited cancer risk condition. The Centers for Disease Control and Prevention (CDC) provides useful information on collecting your own Family Health History.

I wondered to what extent a family history of cancer might stem from members of a family having been exposed to the same environmental hazards (within their home and/or within their neighborhood) while living in the same household.

Friedman and Quesenberry (2000), Hemminki and Jiang (2002), Wieres et al. (2011), Hemminki et al. (2011), and Frank et al. (2016) have looked into this by comparing Concordant and Discordant cancers (cancers of same versus different sites) in families. Their results seemed to be generally inconclusive (to my understanding), with Frank et al. (2016) noting that “environmental risk factors shared by family members are difficult to demonstrate even in the spousal setting, with the exception of smoking related cancers” (p. 6). One of the conclusions drawn by the authors was that “the most likely explanation to the observed clustering of discordant cancers in families is genetic predisposition, possibly with interacting environmental factors” (p. 6).

While looking through these studies it dawned on me that when they used the word “environmental” they were actually talking about smoking, obesity, high calorie intake, and alcohol consumption. The term “shared environment” referred to lifestyle behaviors within the home, not pesticides being sprayed in a nearby orchard or emissions being released through a nearby industry’s smokestack or diesel exhaust from a line of idling buses at a nearby school.

Interestingly, my own experience in medical settings, whether for screening tests or physical exams, is that I have been asked questions about my family members with cancer and my lifestyle choices but have never been asked about any exposures I may have had to toxic hazards outside of my home or in my work environment. Some participants in this cancer mapping project have noted that, while they were going through treatment for cancer, medical personnel were interested in their family history of cancer but were not interested in their environmental exposures when they tried to report them.

Non-Blood Relatives with Cancer

Non-blood family members listed by participants included spouses, step-parents and -children, step-siblings, adoptive parents and children, and in-laws living in the same household.

Of the 1,015 participants on this list who were residents of the White Lake area, there were 109 married pairs in which both spouses had cancer. Of the 109 pairs, there were 96 pairs in which both partners had lived in the White Lake area prior to their diagnosis. There were seven pairs in which both partners had the same diagnosis (five pairs had lung cancer and two pairs had bladder cancer).

Other non-blood related pairs or sets of participants with cancer living in the same household included two step-parent/step-child pairs and two adoptive parent/adopted child pairs. Two sets of in-laws lived in seasonal households, one with two sisters-in-law and the other with a son-in-law and two parents-in-law with cancer. An additional pair of in-laws with cancer had lived on the same property as their son-in-law, whose household had four members, all of whom had cancer.

Extended Family Blood Relatives with Cancer

Extended family members listed by participants included parents, grandparents, great-grandparents, great-great-grandparents, children, grandchildren, great-grandchildren, siblings, half-siblings, aunts, uncles, great-aunts, great-uncles, nieces, nephews, grand-nieces, grand-nephews, and cousins.

The 1,015 participants in this cancer mapping project reported family members in three groups: 1) family members with cancer that were also participants on this list, 2) family members with cancer who had lived in the White Lake area but were not on this list, and 3) family members with cancer that had not lived in the White Lake area.

First-Degree Relatives Living in Same Household

This section looks only at participants and their first-degree family members – parents, children and siblings – that had lived together in the same household during their residencies in the White Lake area and that were eventually diagnosed with cancer. After hearing many stories told by participants about their experiences with pollution in their neighborhood during the industrial period of the 20th century, I wanted to know where, in general, these households were located.

The table below lists the number of households in which first-degree family members that were later diagnosed with cancer and were all participants in this cancer mapping project had lived together in the same household. The numbers listed for each census tract are the number of addresses at which the people had lived according to three categories: addresses at which 2, 3, or 4-6 family members that were later diagnosed with cancer had lived together. For some households, the family members had lived together at two or more addresses, sometimes in different census tracts, so the total number of addresses is larger than the number of households.

Note: Spouses with cancer were mentioned in a previous section, “Participants’ Non-Blood Relatives with Cancer.” The numbers in the above table do not include households in which only spouses (and no children) that later became participants were living in the same household. Spouses are included here only when they were first-degree relatives with other participants: for example, when both parents (who each were a first-degree relative to their child or children) had lived in a household together and were later diagnosed with cancer and became participants in this cancer mapping project.

Most of the shared residences were located in tracts 37 and 38, which include the cities of Montague and Whitehall and the portions of White River, Montague, and Fruitland townships that border White Lake’s shoreline. These two tracts are also where most of the pollution sources were located.

Although their exposures to industrial pollution certainly could have contributed to these participants’ chances of getting cancer, it would be misleading not to mention that many people in this cancer mapping project had smoked. The “Possible Contributors to Cancer” table appearing below notes that 384 of the 1,051 participants were known to have smoked or used tobacco. (Recall that our data on smoking is incomplete, and smoking history is not known for 484 participants that completed their surveys prior to February 2011, unless they or a family member had mentioned it.) In addition to participants that reportedly had smoked, 32 participants mentioned their exposures to secondhand smoke as a child, while 27 people mentioned secondhand smoke as an adult.

I looked at the smoking information for the participants that were first-degree family members living in the same households. Of the 122 households that had two to six participants living at the same residence at the same time:

• in 23 households, both or all of the participants had smoked.
• In 46 households, one or more participants had smoked, while other participants were known to have NOT smoked, and for others their smoking history was not known.
• in 13 households, both or all of the participants had NOT smoked.
• In 40 households, one or more of the participants were known to have NOT smoked, while the smoking history of the others was not known.

Participants’ Lifetime “Possible Causes”

The information summarized in the table below is not limited to the White Lake area, but includes any possible exposures remembered by participants wherever they had lived or worked in their past. The information was gathered from three sources:

• respondents’ answers to a question added to the survey in February 2011: “What things do you think could have contributed to this person’s chance of getting cancer?”
• notes from conversations with respondents
• information drawn from obituaries of participants, including “avid fisherman” and descriptions of their military service

This table does not focus on workplace exposures, although it does mention specific substances to which participants reported that they had been exposed, some of which occurred in work environments. For information on categories of workplaces and the number of participants that worked in each category, see the Workplaces section of this report.

With the exception of the question about smoking, which was added to the survey in 2011, the categories listed below were created after the surveys had been completed to organize and summarize the wide range of information that had been provided by the participants. For example, there was no question on the survey about whether or not the participant swam in White Lake, yet 59 respondents mentioned swimming or boating in White Lake as a concern. The numbers include reported possible exposures – as children or adults – that had taken place as far away as Alaska, California, New Mexico, and New York. Again, these numbers are out of 1,015 total completed surveys.

1. Question about tobacco use was added to the survey in February 2011, after 484 surveys had been completed. Before the question about smoking was added, many respondents had offered the information that their family member with cancer had smoked. Of the 1,015 participants, 384 were known to have smoked or used tobacco (number of years of smoking ranged from 1 to 70), and 252 participants were known not to have smoked. For 379 participants it is not known whether or not they smoked: either their survey was completed before the question was added, or the respondent (such as a grandchild or niece or nephew) did not know whether the person had ever smoked.

2. Substances mentioned, in order of frequency: Agent Orange, paint, trichloroethylene, chlorine, diesel exhaust, unknown “chemical” or “substance” or “fumes”, hair dyes, formaldehyde expanding foam insulation, tool & die chemicals, acetylene, cadmium, candle-making pigments, carbon tetrachloride, dry cleaning chemicals, dust, wood finish and strippers, impregnation solution, lead, pool chemicals, oil & antifreeze, petroleum-based products, and smoke from indoor wood-burning stoves.