Timely Treatment Can Be Successful for LEMS Linked to Lung Adenocarcinoma, Case Study Suggests

Timely cancer treatment helped stabilize a 63-year-old man for more than six years who had lung adenocarcinoma associated with Lambert‐Eaton myasthenic syndrome, unlike the poor prognosis seen in prior cases, a study reports.

The study, “Successful treatment of advanced lung adenocarcinoma complicated with Lambert‐Eaton myasthenic syndrome: A case report and literature review,” was published in the journal Thoracic Cancer.

Lambert‐Eaton myasthenic syndrome (LEMS) is a rare autoimmune disease in which the immune system mistakenly attacks calcium channels in nerve cell endings, which are needed to control muscle movement. Patients experience muscle weakness affecting mainly the lower limbs, but can also experience problems with speech and swallowing, as well as eyelid drooping.

In about 50% to 60% of cases, LEMS is caused by an underlying cancer, most commonly a small-cell lung cancer. It is thought that the antibodies generated to fight cancer cells wrongly target the calcium channels on nerve cells.

In rare cases, LEMS may be associated with lung adenocarcinoma, which is a form of non-small cell lung cancer. A team of Chinese researchers reported one such case.

The study described a 63-year-old man who was admitted to the hospital complaining of drooping in his left eye for the past 10 days, along with double and blurred vision. He had a history of smoking, high blood pressure, diabetes, and left face paralysis. He also had a pacemaker.

During examination, the patient was unable to frown, but his blood analysis came back normal. A chest imaging scan then showed a nodule in the patient’s left lung, which was diagnosed as lung adenocarcinoma after a biopsy.

Additional exams revealed that the cancer was already in distant lymph nodes and in multiple bone locations, leading to a final diagnosis of metastatic lung adenocarcinoma, complicated by LEMS.

The patient had a mutation in the epidermal growth factor receptor (EGFR) gene, seen in about half of Asian patients with lung adenocarcinoma. He then received treatment with the EGFR inhibitor Iressa (gefitinib by AstraZeneca).

One month after treatment, the tumor was smaller and the man’s eye drooping began to resolve. The patient underwent follow-up examinations to the bones, abdomen, and head every six months, which showed that his condition remained stable — without cancer recurrence or eyelid droop — for more than six years.

The team conducted a literature review to examine additional cases of LEMS associated with lung adenocarcinoma. In all seven cases, patients (ages 56 to 78 years) were diagnosed at advanced stages, and only two were still alive at the time the studies were published, suggesting that these cases often have a poor prognosis.

“LEMS is a rare disease, most diagnoses are associated with cancer, but it is extremely rare in lung adenocarcinoma,” the researchers wrote. “Early diagnosis of LEMS and timely and effective treatment can bring a good prognosis.”