LWBK1006-28 LWW-Govindan-Review December 9, 2011 16:52
388 DeVita, Hellman, and Rosenberg’s CANCER: Principles and Practice of Oncology ReviewANSWERS
Answer 28.1. The answer is B.
Linkage studies have revealed the NF1 gene to reside in chromosome 17q
and the NF2 gene to reside in chromosome 22q. For Turcot syndrome,
the APC gene has been identified in chromosome 5q. For Li-Fraumeni
syndrome, the cancer disposition has been shown to be associated with
chromosomes 17p and 22q.Answer 28.2. The answer is B.
According to data from the Central Brain Tumor Registry of the United
States (1998 to 2002), the proportionate distribution of incidence is
30.1% for meningioma, 20.3% for glioblastoma, 9.8% for astrocytoma,
and 2.3% for ependymoma.Answer 28.3. The answer is A.
Alterations of p53 gene are found in 30% of all three grades of astrocy-
toma. Other reported gene alterations include the amplification of MDM2
or MDM4 gene. Chromosome 9p deletions resulting in loss of the p14
product of the CDKN2A gene have also been reported.Answer 28.4. The answer is D.
Primary (de novo) GBM is associated with age greater than 62 years,
amplified EGFR, wild-type p53, PTEN inactivation, CDKN2A deletion,
and decreased survival.Answer 28.5. The answer is C.
A comprehensive effort to sequence the tumor genome of GBM involved
the sequencing of 20,661 genes for somatic mutations from 22 GBM sam-
ples. This study also integrated results from copy number and expression
analysis of tumor tissue. In addition, to identify previously known dysreg-
ulated gene pathways such as p53, EGFR, and PTEN, this study identified
mutations involving the isocitrate dehydrogenase 1 (IDH1) gene in 11%
of GBM samples. Patients with mutated IDH1 gene were more likely
to be younger and had better prognosis than patients with wild-type
IDH1, the median survival was 3.7 years versus 1.1 years, respectively
(p<.001).Answer 28.6. The answer is C.
Allelic loss of chromosome 1p and 19q occurs in 40% to 80% of grade 2
and 3 oligodendrogliomas. The loss of tumor suppressor genes from these
chromosomes is believed to play an important role in the early stage of
oligodendroglial tumorigenesis.