Unexpected Daily Changes in Tumor Volume during Fractionated Gamma Knife Radiosurgery for Solitary Intraventricular Metastatic Renal Cell Carcinoma: A Case Report

Abstract

For most fractionated stereotactic radiosurgery treatment plans, daily imaging is not routinely performed, because there is little expectation that lesions will change significantly in the short term. However, here, we present the case of an abrupt increase and decrease in tumor volume during fractionated gamma knife radiosurgery (GKRS) for metastatic brain cancer. A 65-year-old man with a history of nephrectomy due to renal cell carcinoma was admitted to our hospital because of mild cognitive disorder and gait disturbance. An initial MRI of the brain demonstrated a 5 × 3 × 4.5 cm-sized, heterogeneously well-enhanced tumor with a large cystic component compressing the left thalamus and corpus callosum near the lateral ventricle. Owing to its large size and proximity to critical structures, we decided to perform 3 fractionated GKRSs over 3 consecutive days. After the first fraction of 9 Gy with 50% isodose, follow-up MRI the next day revealed an unexpected increase in tumor volume up to 30%. Therefore, the radiosurgical plan was adjusted, and GKRS was performed again using the same dose for the second fraction. The image taken on the third day showed rapid shrinkage of the tumor volume. This case shows that a tumor may change its shape and volume unexpectedly even during the short period of a fractionated GKRS session. Hence, for optimal fractionated GKRS treatment of tumors with the likelihood of an abrupt change in the short term, interval imaging should be considered.

Adaptive radiosurgery based on two simultaneous dose prescriptions in the management of large renal cell carcinoma brain metastases in critical areas: Towards customization

“…In this particular case, the positive clinical and radiographic evolution of Met 1 and Met 2 post-RRR were similar to previous reports from other authors and Sinclair et al [24,[26][27][28][29][30] Unfortunately, a deeper analysis of the kinetic effectiveness of RRR compared to single fraction treatments or other oligostaged approaches remains complex and will continue to be a source of bias; indeed, although a few groups have studied the specific effects of stereotactic hypofractionated radiotherapy on tumor kinetics in renal histology, [33,37] to the best of our knowledge, there are no or few studies comparing the ablative dynamics of brain lesions post single fraction versus post hypofractionation. Nonetheless, based on (i) the volumetric data post treatment of this case [Tables 1-3] (ii) our institutional experience, [26][27][28][29][30] and (iii) the available medical literature, [1,24,32,36] we suggest that, in the context of this case, the expeditious and lasting ablative effects triggered by this double prescription technique extended survival. [24,[26][27][28][29][30] Moreover, the fact that our patient developed an ARE at the site of Met 1 and Met 2 despite a hypofractionated approach, suggests that SF-GKRS would have led to greater perilesional edema and possibly substantial radionecrosis resulting in further neurologic damage.…”

“…Nonetheless, based on (i) the volumetric data post treatment of this case [Tables 1-3] (ii) our institutional experience, [26][27][28][29][30] and (iii) the available medical literature, [1,24,32,36] we suggest that, in the context of this case, the expeditious and lasting ablative effects triggered by this double prescription technique extended survival. [24,[26][27][28][29][30] Moreover, the fact that our patient developed an ARE at the site of Met 1 and Met 2 despite a hypofractionated approach, suggests that SF-GKRS would have led to greater perilesional edema and possibly substantial radionecrosis resulting in further neurologic damage. Several studies seem to support the latter proposal.…”

“…[5,8,16,21,38] In the realm of brain radiotherapy, focal high dose radiation remains the cornerstone of treatment for unresected radioresistant metastases, such as mRCC brain lesions. [13,21,22,24] In the latter context, SF-GKRS is a well-established modality able to achieve optimal local control rates. [3,15,16,18,20,22,25,35,38] However, as demonstrated here, in the context of metastases larger than 8-10 cc and/or occurring in a critical location, ARE-development secondary to SF-GKRS remains a concern.…”

Solitary metastasis from renal cell carcinoma to the choroid plexus: A case illustration and review of the literature

“…For instance, recent evidence shows how fractionated SRS could be used for large intraventricular metastases if the patient has a poor Karnofsky score. [ 19 ] Nonetheless, when multiple lesions are identified with at least one measuring >4 cm, craniotomy followed by whole-brain radiotherapy treatment yields the best results in terms of overall survival. [ 22 ] Furthermore, preoperative embolization of the choroid plexus may help limit the blood loss and allow total resection.…”

Gradual and Remarkable Tumor Shrinkage Following Seven-Fraction Stereotactic Radiosurgery Alone With a Marginal Dose of 48.3 Gy for Large Lobar Possibly Intra-sulcal Brain Metastasis From Renal Cell Carcinoma

“…Considering the risk of hemorrhage from RCC-BM under DOAC administration, everolimus as a second line therapy was initiated two days after initiation of SRS. T2-weighted images (T2-WI) were acquired at completion of SRS to evaluate potential tumor changes and/or deviation during SRS and showed no obvious change of the tumor configuration [12,18], although a slight dorsal displacement of the tumor owing to slight mitigation of the peritumoral edema was observed (Figures 3A-3D). Although thrombocytopenia and elevated D-dimer improved to 166,000/μL and 14.2 μg/mL, respectively, the neurological and general condition of the patient remained stable at SRS completion.…”