High prevalence of osteoblastic bone reaction in computed tomography scans of an European Organisation for Research and Treatment of Cancer prospective randomised phase II trial in extensive stage small cell lung cancer

Osteoblastic Bone Reaction Developing During Treatment With Sintilimab and Bevacizumab in a Patient With KRASG12V-Mutant Lung Adenocarcinoma

Osteoblastic bone reaction, the occurrence of new osteoblastic lesions, is a paradoxical phenomenon during the treatment of cancers and can be defined as disease progression or bone metastases. Osteoblastic bone reactions usually occur in patients who receive treatments such as chemotherapy or hormonal or targeted therapy; however, it is difficult to differentiate them from disease progression or an increase in osteoblastic activity in response to therapy. Although osteoblastic bone reaction in lung cancer has been described in a few reports, it has never been reported in patients with KRASG12V-mutant lung adenocarcinoma treated with immunotherapy and antiangiogenesis. Here, we describe a case of a 77-year-old male with KRASG12V-mutant lung adenocarcinoma whose osteoblastic bone response was found during treatment with sintilimab and bevacizumab. We showed the course of the disease as well as systematic imaging manifestations of lung cancer with osteoblastic bone reaction and discussed their mechanisms.

Osteoblastic bone reaction in non-small cell lung cancer harboring epidermal growth factor receptor mutation treated with osimertinib

BACKGROUND

Osteoblastic bone reaction (OBR) refers to an increase in bone density at the site of bone metastasis or the appearance of new sclerotic bone lesions after anticancer treatment. OBR can be misunderstood as disease progression. In this study, we aimed to investigate the prevalence and details of OBR and its association with clinical outcomes in patients with epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) treated with osimertinib.

METHODS

This was a single-center, retrospective cohort study. We reviewed patients who were diagnosed with EGFR-mutant NSCLC with bone metastasis and received osimertinib as a first-line treatment between February 2018 and October 2022. The OBR was evaluated by comparing baseline computed tomography (CT) scans with the first CT scan after treatment initiation.

RESULTS

A total of 45 patients were included in this study. Thirty-seven patients (82%) developed OBR. OBR developed in 94% (n = 16) of patients with sclerotic bone lesions (n = 17) at baseline. Similarly, OBR developed in lytic and mixed bone lesions in 76% and 82% of patients with lytic and mixed lesions, respectively. Progression-free survival (PFS) did not differ significantly between patients with (OBR group) and without OBR (non-OBR group) (median PFS, 24 months vs. 17 months; hazard ratio (HR), 0.62; 95% CI, 0.24-1.6; p = 0.31). In univariate analysis, the OBR group showed a trend toward longer skeletal-related events-free survival (SRE-FS) than the non-OBR group (median SRE-FS, 26 months vs. 12 months; HR, 0.53; 95% CI, 0.21-1.33; p = 0.16). Multivariate analysis showed OBR was a significant independent predictor of SRE-FS (HR, 0.35; 95% CI, 0.13-0.92; p = 0.034).

CONCLUSIONS

OBR developed in most patients with NSCLC and bone metastasis who received osimertinib treatment. The increased incidence of OBR in patients with EGFR-mutant NSCLC with bone metastasis treated with osimertinib should not be confused with disease progression, and treatment decisions should be made carefully.

Osteoblastic bone response mimicking bone progression during treatment with pembrolizumab in advanced cutaneous melanoma

Pembrolizumab is an immune checkpoint inhibitor approved for the treatment of patients with unresectable or metastatic melanoma. Appearance of bone metastases, either osteolytic or osteoblastic, during treatment qualifies as disease progression. We report the case of a 64-year-old White woman with a metastatic melanoma undergoing second-line treatment with pembrolizumab. At first evaluation, after 3 months of therapy, computed tomography scans showed the onset of osteosclerotic lesions and a significant reduction in all the previously identified metastases; on the contrary, a fluorine-18-fluorodeoxyglucose PET showed the normalization of fluorine-18-fluorodeoxyglucose uptake in all the baseline lesions, including bone metastases. Osteoblastic response, consisting of occurrence of new osteoblastic lesions on computed tomography imaging, as a consequence of an osteoblastic reaction of previously undetectable bone metastases, has been reported in some cancers that receive treatments such as chemotherapy, hormonal or targeted therapy. However, it had never been reported in patients with melanoma treated with immunotherapy. An apparent worsening of bone imaging on standard computed tomography scan in patients under checkpoint inhibitor should not lead to modification of treatment strategy, because misinterpretation as disease progression may lead to the premature cessation of a beneficial treatment and finally have a negative effect on patients' clinical outcome.

Osteoblastic progression during EGFR tyrosine kinase inhibitor therapy in mutated non-small cell lung cancer: a potential blunder

AIMS AND BACKGROUND

Bone flare reaction as a sign of response to antineoplastic treatment has been redefined, including the onset of new osteoblastic lesions. If misunderstood as skeletal progression, this finding could lead to erroneous therapy discontinuation, changing the disease clinical course. We aim to describe this clinical phenomenon in patients with advanced non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) gene-activating mutations treated with tyrosine kinase inhibitor (TKI).

METHODS

We retrospectively reviewed the computed tomography scans of 43 EGFR-mutated patients with NSCLC treated with EGFR-TKI, analyzing the bone response in terms of increase in the quantity and/or density of lesions, and assessing objective tumor response to treatment.

RESULTS

Osteoblastic reaction was detected in 10 cases (23%), showing different patterns: dimensional or density increase of known osteosclerotic metastases (pattern A, n = 4); response of previously lytic lesions (pattern B, n = 2); onset of new osteosclerotic lesions (pattern C, n = 4). Seven patients had partial response to TKI treatment, with response rate of 70%, vs 50% of patients with bone metastases without this reaction. No difference in terms of median overall survival or progression-free survival emerged between patients with or without osteoblastic reaction.

CONCLUSIONS

The correct clinico-radiologic interpretation of osteoblastic reaction is crucial to avoid waste of therapeutic lines when TKI treatment has not yet exhausted its potential effectiveness. Clinical implications of ambiguous radiologic findings as described in this study deserve further discussion.

The role of general nuclear medicine in breast cancer

The rising incidence of breast cancer worldwide has prompted many improvements to current care. Routine nuclear medicine is a major contributor to a full gamut of clinical studies such as early lesion detection and stratification; guiding, monitoring, and predicting response to therapy; and monitoring progression, recurrence or metastases. Developments in instrumentation such as the high-resolution dedicated breast device coupled with the diagnostic versatility of conventional cameras have reinserted nuclear medicine as a valuable tool in the broader clinical setting. This review outlines the role of general nuclear medicine, concluding that targeted radiopharmaceuticals and versatile instrumentation position nuclear medicine as a powerful modality for patients with breast cancer.