More and more Swiss people are surviving their cancer. However, as a result, they run the risk of dying from cardiovascular problems. Unfortunately, it is in these patients that the treatment of a heart attack deviates from the guidelines.
The good news first: Switzerland is in a relatively good position in terms of cancer survival compared to other European countries. There is still room for improvement compared with the Nordic countries [3]. But there is no time to rest. Indeed, the bad news is that cancer survivors often present later with heart problems, and Swiss physicians, unlike other patients, seem to treat them differently from the guidelines. To the clear disadvantage of those affected: The mortality rate in hospital is significantly higher.
Differences in treatment
But let’s start from the beginning: the University of Zurich study that produced these results drew on Swiss registry data from a total of 35,249 patients with STEMI and NSTEMI between 2002 and 2015. Of these, 1981, or 5.6%, had a history of cancer, i.e., cancer reported on the Charlson Comorbidity Index.
Several potentially confounding variables, eg, age, sex, Killip class >II, ST-elevation myocardial infarction, and renal disease, were considered. The two resulting groups were appropriately “matched,” i.e., counterbalanced-a common procedure in observational studies to statistically compensate for the lack of randomization. The influence of these factors on the type of medical care provided after STEMI/NSTEMI should thus be excluded. Variables such as hypertension, diabetes, heart failure, history of acute myocardial infarction, and cerebrovascular disease were subsequently equally prevalent in the two groups.
However, it was shown that (former) cancer patients were significantly less likely to receive guideline-compliant therapy [4] for their cardiac condition. This was true for percutaneous coronary intervention (PCI) as well as for P2Y12 antagonists and statins. Beta-blockers and aspirin were given equally frequently to the matched groups (as was CABG). Not only was the number of complications such as cardiogenic shock or bleeding more frequent, but in-hospital mortality was also significantly higher compared to non-cancer patients. The risk increased by 45%, 10.7% vs 7.6% died (OR 1.45; 95% CI 1.17-1.81).
The strongest factor in terms of mortality remained the heart itself – with no difference between the groups.
Why is that?
Until now, almost nothing was known about the medical treatment of Swiss cancer survivors beyond the cancer treatment itself. However, evidence from the United States indicates that survivors of various cancers are more likely to “drop out” of standard health-related screening and prevention efforts, as well as recommended physician follow-up for chronic diseases [5]. Because they were previously in intensive and high-frequency contact with the health care system mostly due to their cancer, their focus may have narrowed to this condition in such a way that other health problems are subsequently “overlooked.” Perhaps the primary care physician is visited less frequently, and instead the specialized oncologist, who is unable (or unwilling) to provide holistic primary care. Perhaps, however, the family doctor in charge thinks: “The patient is already under oncological care” and overlooks the fact that the treating oncologist is primarily concerned with the cancer at hand (and does not consider screening for other types of cancer to be his task).
A therapeutic nihilism could also play a role, the prognosis of cancer survivors or in this case “long-term cancer survivors” (the dividing line is not quite clear with the original English term) is still mostly limited, many of them are already older.
All of these considerations could apply to both the physician and the patient. The latter, in the face of the all-dominating cancer diagnosis, may be too unaware of other health problems or refuse new interventions. One thing is certain: cancer survivors are statistically less likely to achieve recommended targets for influenza vaccinations, screenings for other cancers, follow-ups for heart failure, lipid, diabetes management/prevention, etc.
However, an acute event such as an ACS requiring immediate therapy cannot be “overlooked” (neither by the patient nor by the physician), thus other factors must play a role. But which ones?
Answers follow…
It cannot be due to the guidelines from this area. They are evidence-based and well-established. However, how closely the guidelines are followed in clinical practice depends on several factors. In cases of very limited life expectancy or even severe comorbidities, invasive, extensive or other specific therapies are sometimes dispensed with. While some of these variables were included in the study and thus did not affect the final outcome. However, consistent with previous studies from the registry in question [6], any comorbidities have an impact on presentation, myocardial infarction management, and outcome-including, of course, the cancer conditions in the present study. In addition, some relevant information such as tumor type/stage, time of cancer diagnosis (and thus duration of cancer survival), history of venous thromboembolism, infections, hemorrhagic risk, etc., is missing here – they might have been distributed differently in the two groups and could justify divergent treatment decisions.
It remains unclear whether the increased hospital mortality was actually related to lower statin use and less frequent PCI; previous studies on the topic have not reached this conclusion [7]. The results also differ from US studies in other respects: PCI was not performed less frequently in the cancer group, but CABG was. Statins were given more frequently for this purpose. The Swiss authors refer to different patient characteristics and study periods, which makes a direct comparison with their own study difficult. Due to the lack of details on tumor type/stage, their influence on survival could not be excluded.
One thing is certain: The publication raises many questions. This is by no means the last word on the subject. However, the mere outcome of non-guideline compliant treatment has relevance in any case, as cardiovascular disease is responsible for a substantial proportion of deaths in cancer survivors. Among others, hormone therapies for prostate cancer, anthracyclines, and radiation to the chest increase cardiovascular risk.
In a nutshell
- Cancer survivors are a cardiovascular risk group.
- After myocardial infarction, they are less likely to be treated according to guidelines.
- The reasons for this are currently unclear.
Source: Rohrmann S, et al: Treatment of patients with myocardial infarction depends on history of cancer. Eur Heart J Acute Cardiovasc Care 2017 Sep 19. DOI: 10.1177/2048872617729636 [Epub ahead of print].
Literature:
- Zamorano JL, et al: 2016 ESC Position Paper on cancer treatments and cardiovascular toxicity developed under the auspices of the ESC Committee for Practice Guidelines: the Task Force for cancer treatments and cardiovascular toxicity of the European Society of Cardiology (ESC). Eur Heart J 2016; 37: 2768-2801.
- Armstrong GT, et al: Modifiable risk factors and major cardiac events among adult survivors of childhood cancer. J Clin Oncol 2013 Oct 10; 31(29): 3673-3680.
- Sant M, et al: EUROCARE-4. survival of cancer patients diagnosed in 1995-1999. results and commentary. Eur J Cancer 2009; 45: 931-991.
- Steg PG, et al: ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 2012; 33: 2569-2619.
- Earle CC, Neville BA: Under use of necessary care among cancer survivors. Cancer 2004; 101: 1712-1719.
- Fassa AA, et al: Impact of comorbidities on clinical presentation, management and outcome of patients with acute coronary syndrome. Cardiovasc Med 2010; 13: 155-161.
- Yusuf SW, et al: Treatment and outcomes of acute coronary syndrome in the cancer population. Clin Cardiol 2012; 35: 443-450.
InFo ONCOLOGY & HEMATOLOGY 2018; 6(1): 2-3.
