Given that I may need a postchemo RPLND also, I did a bit of research on this. I spoke to the surgeon who does these in the UK, and of the 350 he has done, 15% (about 1 in 7) had residual cancer, hence the need for further chemotherapy. This compares well with the 1 in 8 you have been told.
However, when I delved a bit deeper, the 1 in 7 is across the board, and will include patients across the whole risk spectrum. Therefore, if you are a good risk patient with prechemotherapy low tumour markers and RP mass, then you are likely to have lower odds of further chemotherapy after RPLND than a patient with very high markers and a very large RP mass.
I've posted below a summary of two articles where remaining cancer after postchemo RPLND was much lower than what you've been quoted. The first one found only 1 in 35 residual cancer after postchemo RPLND for stage IIa/IIb disease. The second found 6 in 87 with residual cancer after postchemo RPLND (and 3 of those used carboplatin which is less effective than cisplatinum).
Between 1979 and 1989, 122 patients with clinical stage II testicular nonseminoma were treated with primary platinum-based combination chemotherapy following orchiectomy. Of the patients 58 had Royal Marsden Hospital stage IIA (nodes less than 2 cm. in diameter) and the other 64 had stage IIB (nodes 2 to 5 cm. diameter) disease. With a median followup after chemotherapy of 5.5 years, 118 patients (97%) were disease-free. Two patients died of progressive germ cell tumors, 1 of bleomycin toxicity and 1 of coincidental disease. The 5-year actuarial survival probability was 95% (95% confidence intervals 91 to 99%) and the 5-year failure-free survival probability was 92% (95% confidence intervals 88 to 97%). Tumor substage was not predictive of relapse but did indicate the probability of lymphadenectomy for a post-chemotherapy residual mass since this was performed in 17% of the patients with stage IIA disease and 39% with stage IIB disease (p < 0.05). Resected specimens contained mature teratoma (29), necrosis alone (5) or embryonal carcinoma (1). We conclude that for these clinical stages primary chemotherapy was as effective as primary lymph node dissection and a major operation was avoided in 68% of the cases.
Purpose: To determine preoperative parameters that predict the histology of specimens obtained by retroperitoneal lymph node dissection (RPLND) in patients with nonseminomatous germ cell cancer (NSGCT) whose residual mass was 20 mm in diameter after modern cisplatin-based induction chemotherapy.
Patients and Methods: Eighty-seven patients with metastatic NSGCT underwent RPLND after having received cisplatin- or carboplatin-based induction chemotherapy. In all patients, the largest diameter of the residual mass on the transaxial plane was 20 mm, as assessed by abdominal computed tomography (CT) immediately before RPLND.
Results: Complete fibrosis or necrosis was found in 58 patients (67%), teratoma was found in 23 patients (26%), and vital malignant germ cell tumor was found in six patients (7%), including one patient with rhabdomyosarcoma in the RPLND specimen. In five of the six latter patients, the residual lesion was 10 mm at pre-RPLND CT. No pre- or postchemotherapy clinical or radiologic parameter was identified that significantly predicted the histology of the residual mass.