Patterns of clinicopathological features and outcome in epithelial ovarian cancer patients: 35 years of prospectively collected data

OBJECTIVE

Investigate the clinical landscape of ovarian carcinoma (OC) over time.

DESIGN

Register-based prospectively collected data.

SETTING

South East Scotland.

SAMPLE

A total of 2805 OC patients diagnosed in 1981-2015.

METHODS

Survival times were visualised using the Kaplan-Meier method; median survival, 5-year survival probabilities and associated restricted mean survival time analyses were used to quantify survival differences.

MAIN OUTCOME MEASURES

Disease-specific survival.

RESULTS

A significant increase in disease-specific survival (DSS) from 1981-1985 to 2011-2015 was observed (median 1.73 versus 4.23 years, P < 0.0001). Corresponding increase in progression-free survival (PFS) was not statistically significant (median 1.22 versus 1.58 years, P = 0.2568). An increase in the proportion of cases with low residual disease volume (RD) (<2 cm RD) following debulking was observed (54.0% versus 87.7%, P < 0.0001). The proportion of high grade serous (HGS) cases increased (P < 0.0001), whereas endometrioid and mucinous cases decreased (P = 0.0005 and P = 0.0002). Increases in stage IV HGS OC incidence (P = 0.0009) and stage IV HGS OC DSS (P = 0.0122) were observed. Increasing median age at diagnosis correlated with increasing Eastern Cooperative Oncology Group Performance Status (ECOG PS) over time (r = 0.86).

CONCLUSIONS

OC DSS has improved over the last 35 years. PFS has not significantly increased, highlighting that improvement in outcome has been limited to extending post-relapse survival. Distribution of stage at diagnosis, histological subtype and RD following debulking has changed over time, reflecting evolution in tumour classification, staging and optimal debulking definitions (from low RD to minimal or zero RD). Histology, stage, RD and ECOG PS remain reliable outcome predictors. Increasing median age at diagnosis and ECOG PS indicates demographic shifts in the clinical population.

TWEETABLE ABSTRACT

Significant improvement in ovarian carcinoma survival has been seen over time. Most of this improvement is due to an extension of survival following disease relapse.

Analysis of candidate modifier loci for the severity of colonic familial adenomatous polyposis, with evidence for the importance of the N-acetyl transferases

BACKGROUND

We have recently shown that the severity of human colonic familial adenomatous polyposis (FAP) varies in a manner consistent with the action of modifier genes. These modifier genes may harbour common alleles which increase the risk of colorectal cancer (CRC) in the general population. Analyses have suggested several common polymorphisms as risk alleles for CRC.

METHODS

We determined the association between the severity of colonic FAP (151 patients) and polymorphisms in MTHFR, NAT1, NAT2, GSTM, GSTT, cyclin D1, E-cadherin, and APC. All of these loci have been suggested as influencing the risk of CRC. Colonic FAP severity was quantitated as the number of polyps per colectomy specimen, standardised for colon size. We analysed the relationship between disease severity and genotype at the polymorphic site, making allowance for the position of the germline APC mutation.

RESULTS

We identified significant associations between more severe disease and the absence of the NAT1*10 genotype in the whole group of patients. In a subset of patients with germline mutations in the so-called "mutation cluster region", there was an association between more severe disease and the presence of NAT2*fast alleles. In the whole patient set, a relatively strong association existed between more severe disease and possession of both the NAT1*non-10 and NAT2*fast genotypes. There was weak evidence for an association between the APCT1493C allele and more severe disease in the whole patient group. No consistent association with disease severity was found for the other polymorphisms.

CONCLUSION

The severity of colonic FAP may be modified by alleles at the NAT1 and/or NAT2 loci. The identity of any functional variation remains unknown as NAT1*10 appears to be non-functional and there is linkage disequilibrium between alleles at multiple sites within these loci which are adjacent on chromosome 8p22. While evidence from this study cannot be conclusive, our data suggest that NAT1 and NAT2 variants may explain an approximately twofold increase in polyp number in the FAP colon.

Localization of a gene (MCUL1) for multiple cutaneous leiomyomata and uterine fibroids to chromosome 1q42.3-q43

Dominant transmission of multiple uterine and cutaneous smooth-muscle tumors is seen in the disorder multiple leiomyomatosis (ML). We undertook a genomewide screen of 11 families segregating ML and found evidence for linkage to chromosome 1q42.3-q43 (maximum multipoint LOD score 5.40). Haplotype construction and analysis of recombinations permitted the minimal interval containing the locus, which we have designated "MCUL1," to be refined to an approximately 14-cM region flanked by markers D1S517 and D1S2842. Allelic-loss studies of tumors indicated that MCUL1 may act as a tumor suppressor. Identification of MCUL1 should have wide interest, since this gene may harbor low-penetrance variants predisposing to the common form of uterine fibroids and/or may undergo somatic mutation in sporadic leiomyomata.

In situ analysis of LKB1/STK11 mRNA expression in human normal tissues and tumours

The LKB1/STK11 serine/threonine kinase is mutated in Peutz-Jeghers' syndrome and acts as a tumour suppressor. Using northern blotting and RT-PCR, LKB1 has been reported to be expressed widely in human adult tissues, although in Xenopus the expression of its homologue, XEEK1, is apparently restricted to early embryogenesis. In situ hybridization has been used to detect and localize LKB1 mRNA in a variety of adult and fetal tissues and tumours. The results show that LKB1 expression is widespread, but predominant in epithelia and in the seminiferous tubules of the testis. Expression is higher in fetal than in adult tissues. Expression also appears to be higher in many malignant tumours than in normal tissues or benign lesions, although some cancers have lost LKB1 expression, quite possibly as part of the process of tumourigenesis. These data are consistent with a widespread functional role for LKB1 in tissues of most types, and with a role for LKB1 in the pathogenesis of some sporadic cancers. LKB1 expression may primarily be related to the rate of cell replication.

In situ analysis of LKB1/STK11 mRNA expression in human normal tissues and tumours

The LKB1/STK11 serine/threonine kinase is mutated in Peutz-Jeghers' syndrome and acts as a tumour suppressor. Using northern blotting and RT-PCR, LKB1 has been reported to be expressed widely in human adult tissues, although in Xenopus the expression of its homologue, XEEK1, is apparently restricted to early embryogenesis. In situ hybridization has been used to detect and localize LKB1 mRNA in a variety of adult and fetal tissues and tumours. The results show that LKB1 expression is widespread, but predominant in epithelia and in the seminiferous tubules of the testis. Expression is higher in fetal than in adult tissues. Expression also appears to be higher in many malignant tumours than in normal tissues or benign lesions, although some cancers have lost LKB1 expression, quite possibly as part of the process of tumourigenesis. These data are consistent with a widespread functional role for LKB1 in tissues of most types, and with a role for LKB1 in the pathogenesis of some sporadic cancers. LKB1 expression may primarily be related to the rate of cell replication.

Analysis of genetic and phenotypic heterogeneity in juvenile polyposis

BACKGROUND

Juvenile polyposis syndrome (JPS) is characterised by gastrointestinal (GI) hamartomatous polyposis and an increased risk of GI malignancy. Juvenile polyps also occur in the Cowden (CS), Bannayan-Ruvalcaba-Riley (BRRS) and Gorlin (GS) syndromes. Diagnosing JPS can be problematic because it relies on exclusion of CS, BRRS, and GS. Germline mutations in the PTCH, PTEN and DPC4 (SMAD4) genes can cause GS, CS/BRRS, and JPS, respectively.

AIMS

To examine the contribution of mutations in PTCH, PTEN, and DPC4 (SMAD4) to JPS.

METHODS

Forty seven individuals from 15 families and nine apparently sporadic cases with JPS were screened for germline mutations in DPC4, PTEN, and PTCH.

RESULTS

No patient had a mutation in PTEN or PTCH. Five different germline mutations were detected in DPC4; three of these were deletions, one a single base substitution creating a stop codon, and one a missense change. None of these patients had distinguishing clinical features.

CONCLUSIONS

Mutations in PTEN and PTCH are unlikely to cause juvenile polyposis in the absence of clinical features indicative of CS, BRRS, or GS. A proportion of JPS patients harbour DPC4 mutations (21% in this study) but there remains uncharacterized genetic heterogeneity in JPS.

Identification of a novel mRNA species of the LKB1/STK11 Peutz-Jeghers serine/threonine kinase

Germline mutations in the LKB1/STK11 serine/threonine kinase cause Peutz-Jeghers syndrome and this gene is also mutated at a moderate frequency in a wide variety of sporadic tumours. The translated region of LKB1/STK11 (1302bp) codes for a serine/threonine kinase of otherwise unknown function. We report a novel LKB1/STK11 mRNA species which is found at variable levels in all tissues examined. The novel mRNA, which we believe may be an unusual splice variant, consists of a 444bp in-frame deletion of exons 5-7 and part of exon 8. This deletion removes a large part of the kinase domain and comparison with other LKB1/STK11 mutations shows that kinase function is undoubtedly abolished. The role of the novel mRNA species remains unclear, but it retains a putative cAMP-dependent kinase phosphorylation site and may play some regulatory role.

Germline mutations of the LKB1 (STK11) gene in Peutz-Jeghers patients

Germline mutations of the LKB1 (STK11) serine/threonine kinase gene (chromosome 19p13.3) cause Peutz-Jeghers syndrome, which is characterised by hamartomas of the gastrointestinal tract and typical pigmentation. Peutz-Jeghers syndrome carries an overall risk of cancer that may be up to 20 times that of the general population. Here, we report the results of a screen for germline LKB1 mutations by DNA sequencing in 12 Peutz-Jeghers patients (three sporadic and nine familial cases). Mutations were found in seven (58%) cases, in exons 1, 2, 4, 6, and 9. Five of these mutations, two of which are identical, are predicted to lead to a truncated protein (three frameshifts, two nonsense changes). A further mutation is an in frame deletion of 6 bp, resulting in a deletion of lysine and asparagine; the second of these amino acids is conserved between species. The seventh mutation is a missense change in exon 2, converting lysine to arginine, affecting non-conserved amino acids and of uncertain functional significance. Despite the fact that Peutz-Jeghers syndrome is usually an early onset disease with characteristic clinical features, predictive and diagnostic testing for LKB1 mutations will be useful for selected patients in both familial and non-familial contexts.

Allele loss and mutation screen at the Peutz-Jeghers (LKB1) locus (19p13.3) in sporadic ovarian tumours

Germline mutations in the LKB1 (STK11) gene (chromosome sub-band 19p13.3) cause characteristic hamartomas and pigmentation to develop in patients with Peutz-Jeghers syndrome. Peutz-Jeghers syndrome carries an overall risk of cancer that may be up to 20 times that of the general population and Peutz-Jeghers patients are at increased risk of benign and malignant ovarian tumours, particularly granulosa cell tumours. Loss of heterozygosity (allele loss, LOH) has been reported in about 50% of ovarian cancers on 19p13.3. LKB1 is therefore a candidate tumour suppressor gene for sporadic ovarian tumours. We found allele loss at the marker D19S886 (19p13.3) in 12 of 49 (24%) sporadic ovarian adenocarcinomas. Using SSCP analysis, we screened ten ovarian cancers with LOH, 35 other ovarian cancers and 12 granulosa cell tumours of the ovary for somatic mutations in LKB1. No variants were detected in any of the adenocarcinomas. Two mutations were detected in one of the granulosa cell tumours: a mis-sense mutation affecting the putative 'start' codon (ATG --> ACG, M1T); and a silent change in exon 7 (CTT --> CTA, leucine). Like BRCA1 and BRCA2, therefore, it appears that LKB1 mutations can cause ovarian tumours when present in the germline, but occur rarely in the soma. The allele loss on 19p13.3 in ovarian cancers almost certainly targets a different gene from LKB1.

Multiple intron retention occurs in tumor cell CD44 mRNA processing

Markedly increased overall levels of CD44 transcripts and proteins have been recognized in many tumors and the inappropriate expression and abnormal assembly of the CD44 variable exons has been linked to both tumor growth and metastatic potential. We have also previously observed the aberrant inclusion of intron 9 in CD44 mRNA transcripts in tumor tissues. In this study we assessed whether such retention is specific to certain introns or is a more general phenomenon affecting CD44 gene expression in tumor cells. Intron 18 was cloned and sequenced from genomic DNA and the novel sequences analyzed and used to create intron 18-specific probes. The newly characterized intron was found to have consensus 5' splice site and branchpoint sequences but a suboptimal 3' splice site. The status of CD44 intron 18 retention or excision was assessed in a colon tumor cell line (HT29) and in tissue from 20 colorectal tumors and matched normal mucosa. The intron was shown to be retained in transcripts from 15 of the 20 (75%) carcinomas but in only 3 of the 20 (15%) matched normal samples. These results compare with 80% retention of CD44 intron 9 in colonic carcinoma tissue mRNA and confirm that multiple abnormalities of CD44 mRNA processing occur in tumor cells.

Genetic pathways of colorectal carcinogenesis rarely involve the PTEN and LKB1 genes outside the inherited hamartoma syndromes

Germline mutations of the PTEN/MMAC1/TEP and LKB1 genes cause hamartomas to develop in the gastrointestinal tracts of patients with Cowden syndrome and Peutz-Jeghers syndrome, respectively. PTEN mutations may also be responsible for some cases of juvenile polyposis. Histologically, hamartomas appear benign, but there is good evidence that in these syndromes, the hamartomas can progress to colorectal carcinoma. It remains unknown whether or not cancers that develop from hamartomas acquire a spectrum of mutations similar to those in sporadic colon cancers. PTEN and LKB1 are candidate genes for mutations in sporadic colon cancers, either as initiating events in tumorigenesis or providing a selective advantage during tumor growth. Using single-strand conformational polymorphism analysis, we have screened a set of sporadic colon cancers for somatic mutations in PTEN and LKB1. No variants predicted to alter protein function were detected in LKB1, but 1 of 72 cancers showed a somatic mutation in PTEN, together with allele loss. This cancer did not have a detectable APC mutation or allele loss at APC. It remains possible that PTEN and LKB1 are inactivated in other sporadic colon cancers by means such as deletion or promoter methylation. Like BRCA1 and BRCA2, however, it appears that PTEN and LKB1 mutations can cause cancers when present in the germline, but occur rarely in the soma.