Stage IIIB lung cancer: heart inflammation from durvalumab immunotherapy, mistaken at first for tumor spreading to the heart

What happened, in summary

A 79-year-old woman with a smoking history of more than 50 pack-years was diagnosed with Stage IIIB lung squamous cell carcinoma. Testing found no actionable driver mutation, and PD-L1 expression was below 1%. The tumor was touching the heart, so her team included regular heart scans in her follow-up from the start.

She received 2 cycles of carboplatin plus S-1 together with 50 Gy of chest radiation. This was followed by durvalumab every 2 weeks. After 11 durvalumab cycles over 5 months, a routine heart scan showed that her heart’s pumping strength had fallen to about 30%. Fluid had also collected around the heart and in the right chest. Because the lung tumor was so close to the heart, the team first had to determine whether this was cancer growing into the heart or a treatment-related problem.

An urgent heart-muscle biopsy found inflammation caused by the immune treatment and no cancer cells. Durvalumab was stopped. She received high-dose methylprednisolone for 3 days, IV immunoglobulin for 5 days, a slower oral steroid taper, and medicines to support the heart.

Within 1 week, several heart-injury blood tests were improving. By 3 weeks, her heart’s pumping strength had recovered to about 50%, the heart-wall movement had returned to normal, and most of the fluid had disappeared. She remained free of both cardiac decline and lung-cancer relapse for more than 4 years without further anticancer treatment.

She had entered treatment with good daily functioning and no known coronary disease, making the sudden decline in heart function especially concerning.