Brain dose-sparing radiotherapy techniques for localized intracranial germinoma: Case report and literature review of modern irradiation

Endocrine manifestations of paediatric intracranial germ cell tumours: from diagnosis to long-term follow-up

PURPOSE

We examined endocrine manifestations in a cohort of paediatric patients with IC-GCTs at diagnosis and during follow-up, integrating clinical, radiological, histopathological and laboratory data.

METHODS

Diabetes insipidus (DI), growth hormone deficiency (GHD), hypothyroidism, adrenal insufficiency, precocious puberty (PP)/hypogonadism were diagnosed clinically and biochemically. The prevalence of endocrine manifestations was compared to survival rates.

RESULTS

Our population included 55 children (37 males, 18 females) diagnosed with IC-GCT with a median follow-up of 78.9 months from diagnosis (range 0.5-249.9). At tumour diagnosis, 50.9% patients displayed endocrinopathies: among them, 85.7% were affected by DI, 57.1% central adrenal insufficiency, 50% central hypothyroidism, 28.5% GHD, 10.7% hypogonadotrophic hypogonadism, 10.7% PP. These patients presented predominantly with suprasellar germinoma. If not diagnosed previously, endocrine disorders arose 15.15 months (1.3-404.2) after end of treatment (EOT) in 16.4% patients. At least one endocrinopathy was identified in 67.3% of subjects at last follow-up visit, especially GHD and adrenal insufficiency. DI, hypothyroidism, and adrenal insufficiency occurred earlier than other abnormalities and frequently preceded tumour diagnosis. Subjects with and without endocrine manifestations who survived beyond 12 months after EOT did not show significant difference in overall survival and progression-free survival (p = 0.28 and p = 0.88, respectively).

CONCLUSION

Endocrinopathies were common presenting symptoms in our population. If present at diagnosis, they often persisted hence after. The spectrum of endocrinopathies expanded during follow-up up to 33.7 years after EOT. Although they did not seem to affect survival rate in our cohort, close lifelong surveillance is mandatory to provide the best care for these patients.

Pineal germinoma in a young adult: A case report

BACKGROUND

Intracranial germinomas (GN) are rare cancers that primarily affect children, making them rarer still in adults. Standard treatment for this neoplasm includes neoadjuvant chemotherapy (NC) followed by radiotherapy (RT) or RT at a higher dose and larger field. These recommendations are based on studies focused mostly on children; it is currently unclear whether this treatment is applicable to adults.

CASE

We present a case of a 23-year-old adult male with no underlying pathologies, drug allergies, or family history of cancer, who presented for medical evaluation with blurred vision, diplopia, forgetfulness, and weight loss starting 3-4 months before the evaluation. Clinical examination indicated Parinaud's Syndrome. Magnetic resonance imaging (MRI) and computed tomography (CT) revealed a pineal tumor with ependymal dissemination in both lateral ventricles, which was causing obstructive hydrocephalus. The patient had surgery consisting of ventriculostomy, Holter shunt insertion, cisternal ventricular intubation, and cisterna magna anastomosis to improve ventricular drainage. Pathology confirmed pineal germinoma. Cerebrospinal fluid cytology and MRI of the axis were negative. Four cycles of NC were given to the patient (carboplatin, etoposide, and ifosfamide), with reduced dosage. Once a partial volumetric response was confirmed, whole-ventricular radiotherapy (WVR) was initiated with a total tumor bed dose of 45 Gy over 25 sessions in 5 weeks. Optimum clinical results were observed, and no short-term (<90 day) radiation toxicity was observed. The patient was able to resume his normal activities soon after treatment. Follow-ups over 2 years post-surgery indicated continued control of the lesion and absence of symptoms except for mild diplopia.

CONCLUSION

Although this is a case report, these data suggest that a reduced NC course and WVR may effectively treat adult GN. This protocol likely decreases the risk of undesirable NC and RT secondary effects, while providing excellent local control; however, using a narrower RT field is not recommended.

Whole-ventricular irradiation for intracranial germ cell tumors: Dosimetric comparison of pencil beam scanned protons, intensity-modulated radiotherapy and volumetric-modulated arc therapy

Background

Whole-ventricular radiotherapy (WV-RT) followed by a boost to the tumor bed (WV-RT/TB) is recommended for intracranial germ cell tumors (IGCT). As the critical brain areas are mainly in the target volume vicinity, it is unclear if protons indeed substantially spare neurofunctional organs at risk (NOAR). Therefore, a dosimetric comparison study of WV-RT/TB was conducted to assess whether proton or photon radiotherapy achieves better NOAR sparing.

Methods

Eleven children with GCT received 24 Gy(RBE) WV-RT and a boost up to 40 Gy(RBE) in 25 fractions of 1.6 Gy(RBE) with pencil beam scanning proton therapy (PBS-PT). Intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans were generated for these patients. NOAR were delineated and treatment plans were compared for target volume coverage (TVC), homogeneity index (HI), inhomogeneity coefficient (IC) and (N)OAR sparing.

Results

TVC was comparable for all three modalities. Compared to IMRT and VMAT, PBS-PT showed statistically significant optimized IC, as well as dose reduction, among others, in mean and integral dose to the: normal brain (-35.2%, -32.7%; -35.2%, -33.0%, respectively), cerebellum (-53.7%, -33.1%; -53.6%, -32.7%) and right temporal lobe (-14.5%, -31.9%; -14.7%, -29.9%). The Willis' circle was better protected with PBS-PT than IMRT (-7.1%; -7.8%). The left hippocampus sparing was higher with IMRT. Compared to VMAT, the dose to the hippocampi, amygdalae and temporal lobes was significantly decreased in the IMRT plans.

Conclusions

Dosimetric comparison of WV-RT/TB in IGCT suggests PBS-PT's advantage over photons in conformality and NOAR sparing, whereas IMRT's superiority over VMAT, thus potentially minimizing long-term sequelae.

Suprasellar Germinomas: 2 Case Reports and Literature Review

BACKGROUND

Germinomas are rare malignant central nervous system tumors, a type of germ cell tumor, according to the 2016 World Health Organization Classification of Brain Tumors. Most of these tumors develop along the midline, most often from the pineal gland, followed by tumors arising in the suprasellar cisterns. Suprasellar germinomas commonly manifest with diabetes insipidus, visual impairment, and hypothalamic-pituitary failure. We present a literature review from the PubMed database and report 2 cases of suprasellar germinomas.

CASE DESCRIPTION

Both pediatric patients presented with progressive visual loss; one did not show endocrinologic impairment, and the other presented with hypothyroidism, diabetes insipidus, and generalized edema. Magnetic resonance imaging showed expansive suprasellar masses in both cases, confirmed as germinomas at histopathologic examination. The patients were treated with the same surgical approach, although their outcomes were different because of endocrinologic and post surgical complications.

CONCLUSIONS

Suprasellar germinomas are highly curable lesions when diagnosed early. The treatment remains controversial and should be individualized, but the association of chemotherapy and radiotherapy allows reduce adverse effects and shows great results.