Hypotension, commonly known as low blood pressure, is a condition where the force of blood against artery walls is lower than usual. Generally, a blood pressure reading under 90/60 millimeters of mercury (mm Hg) is considered hypotensive. While some individuals might not experience any noticeable effects, a significant drop in blood pressure can manifest as symptoms like dizziness, lightheadedness, or even fainting. This is a frequent concern for cancer patients, influenced by their illness and treatment.
How Cancer Itself Lowers Blood Pressure
Cancer can directly contribute to low blood pressure through several mechanisms. The presence of cancer significantly increases the risk of orthostatic hypotension, a sudden drop in blood pressure upon standing. Studies indicate that having cancer can double this risk compared to individuals without cancer.
Advanced cancer, particularly with widespread disease, can lead to fluid shifts within the body. Large tumors may alter fluid distribution, reducing the circulating blood volume and subsequently lowering blood pressure.
Paraneoplastic syndromes, rare disorders triggered by an altered immune response to a tumor, can also induce low blood pressure. These syndromes involve the immune system attacking normal cells, including those in the nervous system that regulate blood pressure. Tumors affecting specific organs, such as the adrenal glands, can impair their ability to produce hormones essential for blood pressure regulation, leading to a decrease in systemic blood pressure.
Impact of Cancer Treatments
Cancer therapies can significantly influence blood pressure, often leading to hypotensive episodes. Chemotherapy agents can contribute to low blood pressure through various pathways. Some drugs may directly affect heart function, causing cardiac toxicity that impairs the heart’s pumping ability. Chemotherapy can also induce severe nausea and vomiting, leading to fluid loss and dehydration, which directly reduces blood volume and blood pressure.
Radiation therapy, depending on the treated area, can also have an impact. When radiation is directed at the chest or abdominal regions, it can inadvertently affect the heart and blood vessels. This can lead to changes in cardiovascular function that result in lower blood pressure readings.
Surgical interventions for cancer also carry a risk of hypotension. Blood loss during or after surgery can significantly reduce circulating blood volume. Additionally, anesthetic agents used during procedures can cause blood vessels to dilate, leading to a drop in blood pressure. Fluid shifts within the body following extensive surgeries further contribute to this effect.
Newer treatments, such as targeted therapies and immunotherapies, can also have cardiovascular side effects. Some targeted drugs may interfere with blood vessel tone or lead to inflammation that disrupts blood pressure regulation.
Related Conditions and Complications
Beyond the direct effects of cancer and its treatments, several related conditions common in cancer patients can indirectly lead to low blood pressure. Dehydration is a frequent cause, often resulting from treatment side effects like nausea, vomiting, or diarrhea. Poor oral intake due to appetite loss or mouth sores, along with fever, can also contribute to significant fluid loss, reducing overall blood volume.
Infection, particularly severe systemic infections known as sepsis, can cause a dangerous drop in blood pressure. Sepsis triggers a widespread inflammatory response, leading to extensive vasodilation and increased capillary permeability, which causes fluid to leak from blood vessels. This results in a rapid and substantial decrease in blood pressure.
Anemia, characterized by a reduced number of red blood cells, is another common issue in cancer patients due to the disease itself or chemotherapy. A severe reduction in red blood cells means less oxygen is delivered to tissues, and the heart may struggle to compensate, potentially leading to lower blood pressure.
Adrenal insufficiency, where the adrenal glands do not produce enough hormones, can also occur due to cancer or its treatments. These hormones are crucial for maintaining blood pressure, and their deficiency can result in persistent hypotension.
Severe pain experienced by cancer patients can impact blood pressure regulation. Additionally, certain pain medications, particularly opioid analgesics, are known to cause vasodilation and can lead to a reduction in blood pressure as a side effect.
When to Contact Your Doctor
Recognizing the signs of low blood pressure and knowing when to seek medical attention is important for cancer patients. Symptoms that warrant contacting a healthcare provider include dizziness, lightheadedness, or feeling faint. Other indicators may include blurred vision, confusion, or a feeling of unusual tiredness.
A rapid or irregular heartbeat can also signal that blood pressure is too low. If fainting occurs, or if symptoms are severe and sudden, immediate medical attention is necessary. Prompt communication with the healthcare team about any new or worsening symptoms allows for timely assessment and management.