There are a few conditions that can go undiagnosed because there were no symptoms seen during the primary check-ups. These conditions are also known as "silent killers" and can cause serious complications or death if the treatment is neglected or delayed. Some diseases like cancer and hypertension disguise their warning signs and progress to an advanced stage before they are discovered. Let’s take a look at four such examples.

Pancreatic cancer

Pancreatic cancer is known as a silent killer for good reason. Patients with this disease are often asymptomatic until the disease has metastasised to other organs, notes the Mayo Clinic. By the time they are diagnosed, the cancer is in advanced stages and it’s too late to receive effective treatment. And early detection methods are still lacking. 

Authors of a high-powered case-control study published in PLOS One quoted,

“With a 5-year survival proportion below 10%, pancreatic cancer is the deadliest solid organ cancer. If current trends continue, pancreatic cancer will become the second leading cause of cancer death by 2030."

When symptoms do arise, they are often metabolic and gastrointestinal in nature. For instance, patients who present with newly diagnosed diabetes have four times or greater risk of a pancreatic cancer diagnosis within the next 2 years. Possible nonspecific symptoms include unintentional weight loss in those with pancreatic ductal adenocarcinoma (PDAC). PDAC can also be mistaken for pancreatitis.

In the PLOS One study, researchers attempted to determine whether the development of pancreatic adenocarcinoma could be predicted by a model of 16 risk factors and prediagnostic symptoms of pancreatic ductal adenocarcinoma, as evidenced in Medicare claims data. 

The authors concluded:

“The model provides some information bearing upon the emergent diagnosis of pancreatic cancer, but not enough on its own to be useful in population screening. Excluding the final 3 months of claims prior to PDAC diagnosis reduced the discriminative performance of the model appreciably. Future models should consider sensitivity analyses excluding health changes noted in the final months of PDAC diagnosis in order to evaluate true clinical utility of prediction models for PDAC early detection.”

Silent heart attack

Silent ischaemia may present with either no symptoms, minimal symptoms, or unrecognised symptoms. Symptoms include:

• Feelings of indigestion
• Feelings of a strained muscle in the chest/upper back
• Heavy fatigue

High-risk populations include women and those with diabetes. Silent heart attacks are often discovered only when a patient is receiving an EKG, echocardiogram, or cardiac MRI for another issue.

Results from a high-powered prospective study published in the Journal of the American College of Cardiology indicated that silent myocardial infarction is linked to an increased risk of heart failure, despite other risk factors for heart failure.

The authors wrote,

“Identifying a new potential mechanism contributing to this pandemic is of enormous importance. Although future research is needed to examine the cost-effectiveness of screening for SMI [silent myocardial infarction] as part of HF [heart failure] risk assessment, we believe that our report provides novel insights into an overlooked and potentially addressable contributor to the HF pandemic.”

Colorectal cancer

The symptoms of colon cancer including stomach cramps and unintentional weight loss are often subtle and don’t usually present until advanced disease. Moreover, awareness of the risks of colorectal cancer is low, and it is rarely a beneficiary of high-profile fundraising campaigns.

Although more effective screening has led to an overall decrease in the incidence and mortality of colorectal cancer, rates are rising. One effective means of preventing this silent killer is diet, according to the authors of a review published in Nutrients. Specifically, the authors pointed to the benefits of vitamin D.

They wrote:

“Epidemiological studies have suggested a protective role for Vitamin D in the development of colorectal cancer. Both free and total 25-hydroxyvitamin D was shown to be inversely associated with colorectal cancer. A 10 ng increase in circulating Vitamin D level was associated with a 26% decreased risk of developing colorectal cancer.” 

The authors noted that definitive randomised controlled trials are needed to define risk factors that may play preventive and prognostic roles in this type of cancer. 

Hypertension

Despite high numbers of people suffering from hypertension, only half the people have their blood pressure under control. People in their 30s and 40s are often diagnosed, but in light of the obesity epidemic, younger children are also being affected.

Increased blood pressure places the patient at increased risk of stroke, heart attack, and heart failure. There are often no signs and symptoms of this disease, and early detection is crucially important to institute lifestyle changes and pharmacotherapy.

Antihypertensive medications can take several days to begin working. Many patients have trouble remembering to take these drugs. The FDA recommends that “combination medicines, long-acting or once-a-day medications, may be used to decrease the burden of taking numerous medications and help ensure medications regularly.” In a related topic, drug-induced hypertension is a serious and underappreciated problem, especially in those already taking antihypertensive drugs. 

This story is contributed by Naveed Saleh and is a part of our Global Content Initiative, where we feature selected stories from our Global network which we believe would be most useful and informative to our doctor members.