Long-term outcomes following resection of retroperitoneal recurrence of colorectal cancer.

BACKGROUND: The role of curative-intent surgery for retroperitoneal recurrence (RPR) of colorectal cancer (CRC) remains controversial. We previously showed 0% mortality and acceptable morbidity in patients who underwent resection of RPR.(1) Here we examine long-term overall and disease-free survival (OS, DFS). METHODS: We identified patients who underwent resection for RPR of CRC between 01/1999 and 02/2010 from two prospective CRC databases. RESULTS: The study cohort was composed of 48 patients (26 women) whose median age was 60 (36-80) years. Eleven patients had previously undergone resection of a different focus of disease recurrence, and 8 patients had additional site(s) of distant metastatic disease at the time of RPR resection. Following surgery for RPR, 5 patients were left with gross residual disease, and 6 had microscopically positive margins. Median follow-up was 32 (3-127) months. At last follow-up, 13 patients had died of cancer and 1 of other causes. For the entire cohort of 48 patients, 5-year OS was 70% (median 80 mo). In univariate analysis, OS was reduced in younger patients (p = 0.003) and in those with gross residual disease (p = 0.033). In patients who had grossly complete resection, 5-year DFS was 49% (median 38 mo). Predictors of reduced DFS on multivariable analysis were young age and R1 resection. CONCLUSION: OS and DFS after resection of RPR in well-selected patients were favorable. Patients with RPR of CRC should be considered for curative-intent surgery with careful discussion at multidisciplinary cancer conference.

Spinal segmental somatosensory evoked potentials in lumbosacral radiculopathies.

We studied 21 patients with lumbosacral radiculopathy with segmental somatosensory evoked potentials (SEPs) recorded over both spine and scalp following saphenous, superficial peroneal, and sural nerve stimulation. Spinal SEPs were abnormal in 10 patients. In 3 patients, SEPs detected abnormalities not seen on EMG examination. With 1 exception, all anatomic levels of SEP abnormalities matched that of radiographic, EMG, or clinical abnormalities. SEPs were abnormal in 41% of nerve roots shown to be involved by other techniques. SEPs added to the clinical evaluation in 4 patients, but were less accurate than a combination of EMG and radiography in indicating the extent of nerve root involvement. We conclude that spinal SEPs following segmental sensory stimulation are useful in the evaluation of lumbosacral radiculopathies and complement information provided by the EMG. In contrast, scalp-recorded segmental SEPs rarely provide additional useful clinical information.

Spinal somatosensory evoked potentials following segmental sensory stimulation. A direct measure of dorsal root function.

Dorsal root function cannot presently be measured directly. The H-reflex is an indirect measure of dorsal root function but only for the S1 root. Spinal somatosensory evoked potentials (SEPs) following dermatomal stimulation of the legs have the potential of providing direct data reflecting dorsal root function but have not been reliably recorded in normal subjects. We have developed a reliable technique for recording SEPs at the lumbar root entry zone following segmental sensory stimulation of the legs. The saphenous, superficial peroneal, and sural nerves were stimulated representing the L3/L4, L5 and S1 roots respectively. Reproducible responses (N-wave) were recorded over the lumbar spine in all 60 normal limbs examined. The N-wave peak latency was significantly correlated with lower limb length. The conduction velocities from the stimulation sites to the lumbar spine were similar to published values for peripheral conduction velocities in these nerves. The mean inter-limb latency differences for the N-wave peak were: L3/L4 0.61 msec; L5 0.35 msec; and S1 0.57 msec. The mean N-wave amplitudes were: L3/L4 0.11 microV; L5 0.28 microV; and S1 0.23 microV. This technique is a direct measure of dorsal root integrity. Unlike scalp recorded SEPs, the lumbar N-wave is not state-dependent and is unaffected by lesions within the brain and rostral cord.

Fluorescence studies of Hoechst 33342 with supercoiled and relaxed plasmid pBR322 DNA.

The fluorescence properties of Hoechst 33342 (HO 33342) were examined with plasmid pBR322 in the supercoiled (Form I) or relaxed covalently closed circular (Form Io) conformation in order to determine whether qualitative or quantitative differences in fluorescence properties might provide an assay for topological states of DNA. It was found that HO 33342 exhibited a 30% greater fluorescence intensity with Form I pBR322, independent of the dye or DNA concentration. As the dye to DNA ratio was increased, a red shift of approximately 8 nm was observed for HO 33342 complexed with Form I or Form Io. The red shift in fluorescence emission occurred at higher HO 33342 concentrations with Form I vs. Form Io DNA; however, when Form I and Form Io were mixed in various proportions, neither the fluorescent intensity differences nor the HO 33342 concentration at which the wavelength shift occurred could be used to quantitate the relative proportions of topological states present. These results suggest that although the fluorescence properties of HO 33342 complexed with Form I DNA are different than those of HO 33342 complexed with Form Io DNA, the fluorescence assay is not sufficiently sensitive to quantitatively discriminate among a mixture of DNA in various topological states.