Anatomical Variations: Inherent Challenges in Comprehending Cancer

Prairie Doc Perspective Week of August 16th, 2026
Anatomical Variations: Inherent Challenges in Comprehending Cancer
By Ethan L. Snow, PhD, MA
Human anatomy is fascinatingly and frustratingly complex. In each body, 600 muscles, 206 bones, and 360 joints provide structural stability and movement; two lungs circulate air through 1,500 miles of airways to 480,000,000 alveoli with every breath; one heart circulates 5-6 liters of blood through 60,000 miles of vessels every 30 seconds; 600 lymph nodes activate the immune system and filter foreign invaders (e.g., bacteria, viruses), cellular debris, and cancer cells coursing through 100,000 miles of lymphatic vessels; and the list continues.
As human anatomy applies to clinical medicine, some concepts are fundamentally more conceivable than others. For example, if an individual breaks a bone, they can often logically identify the etiology, understand the inhibited function, and realize the immediate need for urgent care. A radiologist would then localize and visualize the fracture, and an orthopedic surgeon would reduce and fix the bone. Cancer, however, is generally more arduous to conceptualize.
Cancer develops from a single cell, and comprehending the size of one cell is inherently challenging. There are around 30,000,000,000,000 (30 trillion) cells that compose each human body, and the average cell diameter is about 5 micrometers. For reference, the smallest object an unaided human eye can identify is approximately 100 micrometers (0.1 millimeters, or comparatively about one-tenth the thickness of a standard office staple), so it would take about 8,000 average-size cells arranged in a 20x20x20 cluster to be perceived by the naked eye as a minimally visible “speck.”
A single cell becomes cancerous when it acquires a mutation in its genetic code that causes it to grow and divide uncontrollably, ultimately creating many copies of its dysfunctional self. The microscopic scale at which this initially occurs makes it highly implausible to notice, and this is why signs and symptoms of cancer do not present until replication has created enough cellular mass to manifest physical or functional effects. To complicate matters further, while cancer can develop essentially anywhere in the body, cancer cells can relocate (metastasize) throughout the body via the extensive vascular, respiratory, and lymphatic pathways.
Thorough surface examinations (e.g., skin observation, breast/testicle self-exams, digital rectal exam, colonoscopy) are important routine screening procedures, and specialized imaging techniques (e.g., CT, MRI, PET, US) can confirm the presence and location of suspicious lesions (abnormal tissues). A biopsy of an alleged cancer tissue is normally collected to allow a pathologist to observe the associated cells, much like how a radiologist views bones in radiographs. A histologist slices the tissue thinly (~5 micrometers thick) and applies pigmented stains so each cell in the plane can be easily examined. A pathologist then inspects the tissue using a microscope to determine if cancer cells are present and what characteristics they exhibit.
Based on the diagnostic findings, an oncologist can establish the best treatment plan with the patient. Unfortunately, as cancer originates as part of the body’s tissues, treatment via surgical resection, chemotherapy, or radiation often also destroys healthy tissue as it is difficult to confidently target all and only the microscopic cancerous cells.
Ethan L. Snow, PhD, MA is a Clinical Anatomist and Associate Professor at South Dakota State University in Brookings, South Dakota. Dr. Snow leads the Snow Lab Research Team – a collaborative and interdisciplinary team of undergraduate students, professional students, faculty, and clinicians who analyze rare and unique clinical cases involving anatomical variations. Follow The Prairie Doc® at www.prairiedoc.org, Facebook, Instagram, YouTube, and TikTok. Prairie Doc Programming includes On Call with the Prairie Doc®, a medical Q&A show (most Thursdays at 7pm, on YouTube and streaming on Facebook), 2 podcasts, and a Radio program (Sundays at 6am and 1pm).