A 57 year-old Chinese man with the complaint of a dry cough for more than 1 month was admitted to the Department of Thoracic Surgery. The patient had a smoking history of over 20 years, smoking two packs per day, and several years' history of hemorrhoids. He had not undergone any surgery before and had no family history of tumor. His physical status score was 0. The chest CT scan on October 9th, 2019 showed a soft tissue shadow on his left lower lobe and a left hilum space-occupying lesion (Figure 1). The masses were consistent on CT imaging, indicating that the one next to the left hilum was an enlarged hilum lymph node. The CT scan also showed an inflammatory lesion and obstructive lesion on the left lower lobe (Figure 1). PET-CT scan on October 9th, 2019 indicated a dorsal segment soft tissue mass on the left lower lobe adjacent to the hilum, with a size of 3.6 cm x 5.2 cm x 4.8 cm and an SUVmax of 25.3, and a basal segment soft tissue mass, with a size of 3.8 cm x 3.6 cm x 3.8 cm and an SUVmax of 12.5 (Figure 1); the masses had an increased metabolic rate and were considered to be malignant lesions. Multiple mediastinal and right hilum lymph nodes were detected with an increased metabolic rate; the lymph nodes were considered to be inflammatory lesions. Otherwise, no distant metastatic signs were exhibited on PET-CT. No abnormal signs were observed on brain MRI, either.
The patient underwent needle biopsy on October 12th, 2019 and the pathologic result showed poorly differentiated squamous carcinoma. The patient refused to take any invasive examinations after needle biopsy, thus mediastinal staging was not performed. The specimen was sent for PD-L1 detection and tumor proportion score (TPS) was 80%, indicating a high expression of PD-L1. Thus, the clinical staging for this patient was cT2aN1M0, IIB according to the 8th edition lung cancer stage classification system. Because of the enlarged lymph node proximal to the hilum, the surgery plan was considered to be pneumonectomy. Thus, in order to reduce the size of the tumor and preserve residual lung function, this patient received neoadjuvant chemotherapy (gemcitabine 1.6 g, d1, d8 plus cisplatin, 60 mg, d1, d2, Q3W). The chemotherapy plan was implemented for five cycles from October 17th, 2019 to March 17th, 2020 and pembrolizumab (200 mg, d1, Q3W) was added from the second cycle. Due to the outbreak of COVID-19, the plan had to be suspended after the fourth cycle. The fifth cycle was initiated on March 17th, 2020. The CT scan on December 6th, 2019 after two cycles of neoadjuvant therapy and March 15th, 2020 after four cycles of neoadjuvant therapy showed shrinking masses on the left lower lobe (Figure 2). During the treatment, the adverse effects in this patient included vomiting, thrombocytopenia, and occasional chest distress. The platelet count of the patient was 61.00 x 109/L on October 31st, 2019. All the symptoms were alleviated after symptomatic treatment. The PET-CT scan on April 28th, 2020 showed the mass adjacent to the hilum on the left lower lobe to be 1.7 cm x 2.3 cm x 2.0 cm, with the SUVmax being 8.4 (Figure 3). The mass on the basal segment was 1.7 cm x 1.8 cm x 1.6 cm, with an SUVmax of 8.4 (Figure 3). Finally, the patient underwent left lower lobectomy on April 30th, 2020 and the intraoperative pathologic report showed a benign lesion of the left lung nodules and no tumor in the resected lymph nodes. The postoperative pathologic result indicated no detected tumor in the resected mass or the lymph nodes. Thus, the patient was evaluated as having a pathologic complete response (pCR).
Postoperative follow-up of the patient was done on June 2nd, 2020, with no recurrent or metastatic signs on chest CT, cranial CT, abdominal ultrasonography, or urinary system ultrasonography. The patient refused postoperative chemotherapy for fear of its adverse effects and received intravenous injection of 200 mg pembrolizumab on June 7th, July 8th, August 3rd, and August 29th, 2020; reported adverse effects included mild cough, vomiting, and decreased platelet count (103.00 x 109/L on August 4st, 2020 and 83.00 x 109/L on August 29st, 2020), which were all alleviated automatically or after symptomatic treatment. Carbohydrate antigen 125 and carcino-embryonic antigen were 22.30 U/mL and 1.33 ng/mL on June 5th, 9.80 U/mL, 0.95 ng/mL on July 6th, 8.50 U/mL, 1.11 ng/mL on August 3rd and 7.90 U/mL, 1.43 ng/mL on August 28th, respectively. Further data were not available. Major events of this case were summarized in Figure 4.