Any oncologist can testify to the difficulties facing family members of patients with cancer.  A recent study out of Canada examines the “biologic cost” of caring for a patient with cancer.  This was a small study in which the researchers compared saliva and blood samples from 18 primary caregivers of people who had just been diagnosed with brain tumors with those from 19 volunteers.  They also used questionnaires to measure perceived stress and depressive symptoms in the caregivers and the volunteers, who were all followed for one year.

   Salivary amylase was used as a proxy for studying activation of the sympathetic nervous system (a.k.a. adrenaline, responsible for the “fight or flight” response).  Normally, this enzyme in saliva declines sharply after awakening and then rises throughout the day.  As expected, this diurnal rhythm was preserved over time in the healthy volunteers.  Caregivers, on the other hand, experienced loss of this normal rhythm over time and then gradual recovery.  C-reactive protein is a measure of systemic inflammation and high levels are a well-documented risk factor for cardiovascular disease.  At the study entry, levels were similar in caregivers and volunteers; however, over time, the caregivers demonstrated increase in CRP.  In fact, half of them developed CRP levels >3 mg/L, a level considered to be a marker for high risk of cardiovascular disease.  CRP levels did not reach a plateau but continued to increase over the year of the study. Over time, caregivers also demonstrated lower expression of anti-inflammatory signaling molecules.

   Interestingly, cortisol output was similar in caregivers and controls, leading the investigators to hypothesize that the sympathetic nervous system rather than cortisol may be directly driving inflammation and suppressing normal anti-inflammatory molecules. On a questionnaire used to evaluate for depression, 67% of the caregivers had scores that indicated depression at the time of study entry.

   What does this study add to our understanding of the experience of being a caregiver for a cancer patient?  The findings are not particularly surprising but, I think, are an important starting point.  The methodology is important: it can be misleading to measure stress responses or hormone levels at a single time point, for example, just after a patient has been diagnosed or during intense chemotherapy and radiation.  This study did follow caregivers over a fairly long period of time and employed multiple measurements at each time point.  The use of a control group also lends credibility to the findings. 

   What can we do with this information? Although it is difficult to do prolonged studies, I think it would be important to continue to follow the caregivers over time.  Since their levels of CRP continued to rise over the year period and had not plateaued at the end of that time period, I think it would be important to try to determine when, if ever, caregivers return to normal.  It would also be important to follow them to figure out if these altered hormonal/inflammatory markers actually led to an increase in cardiovascular disease or other illnesses.  We don’t know whether elevated levels of CRP in someone going through tremendous stress have the same implications as when someone has elevated levels of CRP for no particular reason.  It has been my experience that many caregivers neglect their own health when a family member is going through cancer treatment.  High rates of depressive symptoms were reported in the caregivers but no information is provided about whether any of them got medical treatment/counseling.  A future study might monitor these same biohormonal changes in a group of caregivers given counseling or other treatment for depression.

   Do these findings apply to caregivers of patients with other cancers? This is unknown. Because of the demographics of brain tumor patients, caregivers in this study were much younger (median age 50) than most of the primary caregivers of my lung cancer patients.  I wonder if the effects might be more pronounced in an older population with more medical problems at baseline.  Alternatively, perhaps a brain tumor diagnosis is particularly challenging for caregivers.  It would also be interesting to follow whether there are any correlations between these neurohormonal measures in patients and levels in caregivers.

   I’m glad to see a study like this in oncology, though I think we still have a long way to go towards helping families cope.  Although providing medical care to family members goes beyond the scope of most oncologists’ practice, I think we can at least be more aggressive about enlisting the help of our oncology counselors and social workers.  And put in a plug for family members to continue with regular doctor visits and medical care.

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