What happens when a doctor makes a mistake that delays treatment for a serious disease, but nobody can say for certain whether earlier treatment would have saved the patient’s life?

Does that uncertainty prevent the family from pursuing or winning a Medical Malpractice case?

The Pennsylvania Supreme Court just addressed that question in Smith v. Kannarkatt which was decided on October 29, 2026.

The Supreme Court ruling reinforces an important principle of Pennsylvania Medical Malpractice Law: a patient does not necessarily have to prove that proper medical care would have prevented the ultimate injury or death. Instead, a malpractice case can be successful if the victim proves that a medical professional’s mistake increased the risk of the harm that occurred.

The Facts of the Smith v. Kannarkatt – A Tragic Cancer Misdiagnosis

In March 2017, Tanya Smith had a biopsy of an enlarged lymph node near her armpit. The pathology report suggested metastatic breast cancer. But subsequent testing, including scans and breast imaging, did not identify a breast tumor, which was unusual.  Some of the test results also raised the possibility of lymphoma, a different type of cancer.

Despite the conflicting findings, Smith’s oncologist, Dr. Annie Kannarkatt, proceeded with chemotherapy and radiation directed at breast cancer, not lymphoma. For approximately 13 months, Smith received treatment that did not adequately address the disease she actually had and her cancer continued to spread.

A later biopsy finally revealed the correct diagnosis, a rare and aggressive lymphoma cancer.

Smith then received lymphoma-directed chemotherapy and underwent a stem cell transplant, but she died in January 2019.

Smith’s family filed a Medical Malpractice claim alleging that the oncologist should have questioned the original diagnosis, consulted the pathologist and pursued further investigation before continuing the breast cancer treatment. Smith’s experts testified that the delay deprived Smith of a substantially better opportunity for a longer life, or, stated another way, increased the risk of her dying from cancer.

The Difficult Question of Causation

To win a Pennsylvania Medical Malpractice case, a patient usually must establish that a healthcare provider violated the accepted standard of care and that the violation caused harm. These are separate questions. A medical mistake, by itself, does not automatically establish a malpractice claim. The mistake must also cause harm.

However, in Medical Malpractice cases, proof of causation can become particularly difficult when the patient already had a life-threatening illness. Even with perfect treatment, some patients do not survive. A doctor defending a malpractice case may argue that the disease, not the alleged mistake, caused the death, and even perfect treatment could not have saved the patient.

Should that uncertainty give a negligent medical provider a complete defense? Pennsylvania law says not necessarily.

What Is the Increased Risk of Harm Standard?

In the landmark 1978 decision Hamil v. Bashline, the Pennsylvania Supreme Court adopted what is commonly called the Increased Risk of Harm standard. It applies in appropriate cases where a healthcare provider’s failure to exercise reasonable care increases the risk of harm from an existing danger, such as a serious illness.

Under this Increased Risk of Harm rule, the victim can present qualified expert medical testimony, stated to a reasonable degree of medical certainty, that the provider’s negligence increased the risk of the harm that actually occurred. The jury then decides whether that negligence was a substantial factor in producing the injury or death.

In other words, the expert does not always have to testify that the patient definitely would have survived with proper treatment, or predict exactly how many additional months or years the patient would have lived. But speculation is not enough: there must be meaningful expert evidence connecting the negligent care to an increased risk of harm.

What the Supreme Court Decided in Smith v. Kannarkatt

At trial, the judge dismissed the Smith family’s case before it reached the jury, finding insufficient proof of causation. The Superior Court reversed, and the Pennsylvania Supreme Court agreed that the family had presented enough evidence of Increased Risk of Harm to proceed.

The Supreme Court emphasized testimony that the oncologist failed to investigate findings inconsistent with breast cancer and that the lengthy delay allowed the lymphoma to progress while Smith underwent debilitating, inappropriate chemotherapy. An expert explained that earlier lymphoma treatment offered a substantially better opportunity for a longer life.

The Supreme Court found that the evidence was sufficient to let a jury decide whether the oncologist’s conduct was a substantial factor in Smith’s harm. The Supreme Court did not decide that malpractice had been proven or award damages. Rather, the family was granted a new trial in which it must persuade a jury to win.

Why This Decision Matters

This ruling matters beyond cancer misdiagnosis. Increased Risk of Harm issues can arise in cases involving delayed stroke treatment, missed infections, failure to monitor patients and other situations where prompt care may improve the chance of avoiding a serious outcome.

The lesson is that medical providers cannot escape responsibility for their mistakes just because they can argue that the bad result might have happened anyway. Instead, the Courts recognize that it would be unfair to provide such legal immunity.  Uncertainty about what might have happened should not automatically prevent a Medical Malpractice from being heard and decided by a jury.

Questions About Possible Medical Malpractice?

I have represented injured people and families in Pennsylvania Personal Injury and Medical Malpractice cases for more than 30 years. If you believe a delayed diagnosis, treatment mistake or other medical error caused serious harm to you or someone you love, I would be glad to discuss what happened and whether an investigation makes sense.

I have law offices in West Chester and Kennett Square, Pennsylvania and can be reached at 610-840-0124 or trayne@macelree.com.  You can also check out my website at www.TimRayneLaw.com.